67RModel

Good information to know. Is there any type of safeguard to prevent one axle from shifting if the other solenoid or air shift cylinder fails to operate? I could only imagine the carnage of only one diff shifted and the other did not. Have you ever know that to happen?

You seem to know a lot about two speed diffs. I always thought they should be much more prevalent than they are. I guess with modern engines and auto transmissions they have become almost non existent in new trucks. Are Eaton axles and Dana Spicer axles synonymous? You keep saying Eaton but DT series axles I thought were Dana Spicer. Did one buy the other and they are all the same now? How does downshifting the two speed work? Do you flip the switch while the trans is still in gear and then lift of the throttle to break torque then lay into the throttle to raise rpms until it engages? I drove many single axle 5+2 gasser dump trucks that were like that. They had Eaton "Double Duty" electric shift rear ends. It was actually a very handy setup. They were real clunky going from the high side to the low side (downshifting) the axle. I just wonder if air shift two speed tandems are the same.

Yea I'm not sure how the process worked when you bought a new truck then. I have seen a lot of service manual "sets" that were compiled by Mack for a truck or set of identically specd trucks. The set usually is in a single or group of 3 ring binders that contain many different service manuals for different systems / components depending on what the customer wanted I guess. A lot of times the front of the binder with the parts breakdowns would say for VIN "XXX" or VIN "XXX through "XXX" if it were for a set of identical trucks. There is literally a different service manual for every system or component on the truck. For instance there is one for the engine, injection system, driveshafts, wheel bearings, and wheels. They are all a different publication and not contained in one single book. Like Joey said at a minimum you probably just want to start with a basic E6 engine book, one for your transmission model, and maybe a wiring diagram to get started.

Sometimes you just have to cut your losses and throw in the towel. The information you are searching for has been probably completely lost in with time. There may be someone out there that has old literature or whatever that shows something useful but trying to find that place or person probably isn't a valuable use of your time...no disrespect. They look pretty crusty and dry rotted anyway. No telling as old as they are if they would still meet the published specs if you were able to find them. Sorry but no way would I attempt to run those at 60 mph on a steer axle. Accident waiting to happen.

I think its documented somewhere freshkills landfill is the largest manmade thing on the planet.

Well in USA if the axle centers are 8' apart or greater they can be considered separate (for bridge formula). Since this truck was originally 18,000 front and 38,000 rears you should be fine saying its 41,000 gvw (18 + 23). However, in the federal bridge law the most you can have on any single axle is 20,000 so maybe just say the gvw is 38,000 (18+20). If the truck is a tractor its difficult to get 18,000 pounds on the steer axle since its set forward. If its a dump truck or something else you may be able to max out the steer depending on where the body is located in relation the rear axle center and how its loaded.

Have any of the 100yd dump trucks survived?

I’ve only driven a few trucks with the blue button and never used it. I was always told its only practical purpose was so you could set the tractor brakes only and go back and adjust the trailer brakes without having to release everything and chock the wheels. I don’t know if there were others uses for them or not….

Yea and PA has the second highest gas prices next to Cali I think. They tax the heck out of it and our roads are still mediocre at best. Regular here in Pittsburgh is 3.75 and Diesel is 4.75

Might not be a bad idea given the fact you will never need it for any purpose. I have never had the dash apart in something with a blue valve. Is the valve all one unit with the red and yellow or is off by itself? If your back there gutting out unused stuff and cleaning up poor repairs and workmanship it might be worth it to just get rid of all the old valves and throw a new parking brake valve (yellow button) in it so you know it pops off at 60psi and be done with it. Sounds like you are going to have drivers in it and be using it for actual work. In this case you want everything to be in good condition and as basic as possible.....

If that sucker has minimal rust that would be like $4500 - $5000 all day long around me. After all its a "classic" now lol. I don't know what they actually sell for but that would be listed for $4500 minimum. Even the rust buckets dam near breaking in half are $1500 anymore.

I agree. Its not uncommon to walk onto a lot and find highly optioned half tons for over $70,000. And they stock lots of them so that tells me they sell lots of them. At least in my area all I see is new pickups on the road. Paying $70,000+ and interest on a complete liability, depreciating asset is just plain looney to me. Like you said I purchased a single family rental house for $40,000 a few years back and it generates enough rent to pay the mortgage on itself as well as the mortgage on the house I live in. I could never in a million years justify paying more for a pickup than a house. I paid $17,200 for my used 2009 Silverado back in 2014. That is equivalent to spending $22,200 today. I looked a few months back and the cheapest I saw a excellent condition 5 year old truck was in the mid to low 30s....with a boatload of miles on it. Its crazy out there.

I'm not wondering after reading all this that you got someone else's truck and they got yours? It would be one thing if it was just one item that was incorrect. But it seems like there are many differences in spec than what was ordered. Crazy how that can even happen with all the computer controlled assembly lines, bar codes, and QR codes. Unless it was build during all the "supply chain BS" and they just slapped what they had available on it and got it out the door.....

Kind of irrelevant to the discussion since he is inquiring about CT. In PA there is class A, class B, and class C licenses. Also there is class A CDL and Class B CDL licenses. Technically if you operate a large motorhome with a 33,000 GVW for your pleasure you need a class B license. If your towing a trailer with your pickup that has a gvw higher than 9,999 pounds you need to obtain a class A license. obviously you need a CDL if your engaged in commerce, you drive for a living, etc. Most people don't know about this and pull their 32' 14,000 gvw travel trailers with a regular class C license they got when they turned 16. I don't think anybody cares though. The difference between the class A/B licenses versus the class A/B CDLs is the medical inspection BS, hours of service BS, Pre trip inspection BS, etc. You have to pass the same driving tests as you would a CDL to prove a level of proficiency to operate a large vehicle/combination, however, you are not subject to all the regulatory stuff CDL holders are. But like I said I don't think any law enforcement are pulling guys over towing their RVs, ATVs, or antique tractors looking to see if they have the proper noncommercial license.....

What happened to it after they closed down. I think UPS bought them out right? I can't imagine UPS kept it.....Looks like its in a museum now.

I sent this guy a PM the day after he made this posting to see if he was interested in mine. Never heard anything back from him. And he hasn't logged on since his first post. I'm looking to sell my 1960 B-81 if anybody is interested. Its 90% restored. I have everything to finish the truck. I just don't have the time and no a lot of interest in B models.

Saw these on Facebook Marketplace in Jasper, Indiana. They look like good clean B Models for restoration projects. Frames look very nice to me. Prices are reasonable considering. Looks like they have been stored properly over the years. No affiliation. Just passing along. I included two pictures incase anyone can't open the link. https://www.facebook.com/marketplace/item/1921687911576925/?ref=search&referral_code=null&referral_story_type=post

Yes that was my thought as well. My 1974 Road Boss has the exact same cross members in it......

Did you fabricate that rearmost crossmember? I have never seen a vintage or antique Mack with a crossmember like that..... Looking real good so far.

https://www.macktruckshistoricalmuseum.org/about/historical-research/

Well you could do a couple things. If you get a hold of the Mack museum and request all the build information it may be contained in the papers you get back what the original designed GVW it was specd for. Information I gat back for my 1967 had the designed GVW, designed GCVW, typical payload and top speed desired at max GCVW (it is a tractor). Not sure if you would get the same information or not. I guess it just depends on how the dealer filled out the paperwork or if Mack engineering got involved and the numbers were recorded. You could look at the title and see what GVW its registered at and just assume that over the trucks life it was originally specd for what its titled GVW is. In the end it should not matter too much though. a 690SX is generally going to have pretty hefty specs. I would guess at least 44k rears and a 16k or 18k steer axle. But with the addition of drop axles one can increase the GVW significantly. You can basically make it whatever you want if you are cozy with an inspection mechanic. When I brought by 94 RD690 into PA from Virginia I had to get a PennDOT MV-41 form filled out and signed by an heavy truck inspection mechanic stating that the truck was capable of the GVW I was requesting the truck to be registered for. Its funny though the GVW on the Virginia title was 80,000 and I was wanting to register it for less weight at 73,280 (the most a triaxle can weigh in PA) to save some money on registration fees. I think it was just a formality on the notary's part. But consider if I had bought the truck as a tandem axle with the plan to put a drop axle under it. It would have theoretically been titled at 54,000 GVW. I would have installed a pusher axle on it to make it a tri and had an inspection mechanic inspect it and fill out an MV-41 stating it is now capable of grossing 73280. Not sure what goes on in Ohio though. Probably something similar I would think.

If you really want to get into the weeds with the "procedure" you can get get out your dial indicator when you are all done and check the end play of the hub center while spinning it and shaking it fore and aft. The acceptable tolerance I think is 1 - 5 thousandths of an inch end play 😂. But like other have said if your not blowing out seals regularly your wheels are not flying off.....your good. snug down on the bearing. Back off a little. and torque the snot (by hand) out of the outer lock nut.

And yes like everyone else has said. The Stemco Voyager seal goes in very easy with no special tools required. A block of framing lumber and a large ball peen hammer is all you really need. Of course you need to pay attention to what you are doing and tap it in with lots of care. I actually don't really know or recall what Voyager seal number mine crossed to but my original grit guard seal was 320-2110.......6" diameter.

Also a tip for anyone doing this type of job in a more or less shadetree scenario. Get a 3/4" drive digital torque adapter from Harbor Freight. I debated laying down some serious coin for an average quality 3/4" torque wrench that would go to 350+ ft*lb then I found this handy device for $70. You can basically turn any breaker bar into a precision torque wrench. Everyone has a 1/2" breaker bar laying around. Just get this tool and a 1/2 to 3/4 adapter and you are good to go. I have a 3/4" breaker bar and a long piece of 1" EMT conduit slides nicely over the handle for extra leverage. I was a little reluctant but I found many positive reviews on it that were not on Harbor Freight's website. It's also made in Taiwan not China so the quality and precision is good. https://www.harborfreight.com/34-in-drive-150-750-ft-lb-digital-torque-adapter-58707.html