doubleclutchinweasel

...I'd still like to swap out my tandems for a single rear...

Will do...

If you do a Google search for "Mack engine identification guide", there will be a link to a thread on this website which explains all the nomenclature. I have that .pdf file saved, if anybody can't find it. in fact, I'll attach it here. There was, apparently, a different numbering system prior to 1975, an intermediate system from '75 to '80, and another one introduced in '80. The plain "E" designation started around 1980. That would be E6 for what used to be called Thermodyne and EM6 for what used to be called Maxidyne. And, like you stated, the designation EM6-300 is definitely the easiest to decipher! Since this truck was reportedly a 1970, then there should be an "old" designation on it, like ENDT-675. They did start dropping off the END part at some point. In fact, mine is a '70 with the original engine (S/N verified off the build sheet), and it has already had the END prefix dropped. So, that started a pretty long time ago. Oh, and it DOES, indeed, look more like a 237 than anythiing else. Doesn't it? Kent Engine Model Designations.pdf

I may be off-base here. But, if I am, I'm sure somebody will correct me (with extreme prejudice!). Yes, there may be a data plate on the side of the pump. But, I have seen these go missing or become faded out and unreadable. In the attached image, the arrow shows where there may be a number stamped on the accessory drive case. This is the engine model number and serial number. On this one, (an ENDT-673C - a 250HP Thermodyne), they left off part of the number, and just marked it T 673 C ... and then the serial number. I guess they figured we should already know it is an engine (EN), and that it's a diesel (D)! See if you have a number there. If so, it will give you a lot of info. For instance, I think a 237 Maxidyne would be an ENDT 675. But, then again, I could be wrong... Kent

excellent idea!

Well, I figured, since I had the original Fuller transmission, I'd stay with the Fuller control knob. I hadn't thought about it, but I suppose you are corrct, though. There is probably a Mack knob that would do the same exact thing. I wouldn't mind swapping out the medallion on the knob for a 10-speed shift pattern version. But, those medallions seem to cost almost as much as the knob! That is, IF you can even find them. I wonder if there might be a Mack medalion to fit that Eaton-Fuller knob... Oh, and I agree; those old round knobs are about as cool as you can get!

Hey, Speed. The way this valve is ported is like this. When the range select lever is "down" (LO), the "supply" port is connected to the "delivery" port, which feeds the slave valve/cylinder. When the range select valve is "up" (HI), the "supply" port is closed-off, and the "delivery" port is exhausted to the atmosphere. As long as your 2-speed valve is similarly ported, then I don't see why it wouldn't work. I mean, pressurized air and vacuum are similar systems. They both work on a pressure differential. The primary difference is the AMOUNT of pressure differential you have to work with. With pressurized air, you can get more work out of it. But, if the system is already functioning correctly on vacuum, then the cylinder sizes and mechanical devices are, by definition, already properly sized to do the work required. Remember, the control valve is just that; a CONTROL vavle. It doesn't do the actual work; the cylinders do. So, as long as the porting works like I described above, it SHOULD work. If you are concerned about flow rates, and the associated time/speed of the system, you might consider using slightly larger lines. Mine are the original 1/8" lines. I believe most newer stuff uses larger 5/32" air lines. This will provide slightly more available "buffer" air, which should improve the function slightly. The actual threads in the new valve are 1/16" NPT. So, this may somewhat limit both the maximum airflow through the fittings, and the variety of fittings available. The original T-valve used 1/8" NPT fittings, just for the record. The new valve works exactly as well as the original did on my truck. I can't tell any difference at all with the smaller fittings. But, again, the actual work is being done by the slave valve/cylinder. This valve just tells it what to do! Hope this helps. Let me know if I can clarify (confuse?) the issue any further for you! Kent

But it still might fall over...

MB is one of those trucks that you can't help but like. First time I saw that old MB flatbed, I thought of how ugly it was. But, it kinda' grows on ya'. I guess that's par for the course for us Mack guys. Who else would think a bulldog looks good! The MB just plain looks "tough".

I drove an MB flatbed when I was YOUNG. Steering wasn't too bad...as long as you could get up on the wheel and run around it like a squirrel in a cage!

84superdog (I think it is) has a single-axle MB listed. Kent

Wasn't there a "wanted" post from somebody looking for an MB tractor recently?

Welcome! If nothing else, some of the posts are...uhh...entertaining! Kent

Exactly!

Thanks, everybody! This was a lot more work than welding a bolt on top of the stick. But, it should be very durable...and it's certainly cleaner!

This looks and feels SOOOO much better now! In reverse, it's about the same height as the bottom-right section of the steering wheel.

Finished knob installed.

Set screw in place.

Using jig to file top of stick square and "index" knob.

Drill jig with 1/2-13 tap bushing.

Drill jig with 27/64" bushing.

3/16" pilot hole.

Drill jig in place with 3/16 bushing

Range selector valve is leaking. Old "bat handle" knob is worn through, and too tall. Looks like something off one of Ed Roth's cartoon cars from the '60s! The 5/8-11 to 1/2-13 adapter they used adds another inch or so to it. Picked up a new-style Eaton-Fuller knob, with built-in range valve. Now, I'm making a drill jig to mount on top of the stick (after I cut it off) to allow precise drilling & tapping of the stick. I'm gonna cut the stick off, and drill & tap it to the 1/2-13 thread size on the new knob. Then, I'll put a long grade 8 set screw in the hole, and thread the knob on. Rather than screw the knob on and use jam nuts to lock it in place, I will use a washer of correct thickness to "index" the knob on the stick. That will be a little more work, but it will be VERY clean. I looked at the actual 15-speed knob. But, according to Fuller, you have to change the cover on the deep reduction slave valve on the transmission to make it work. Must be a little different logic to the air circuit. No matter. The hi-lo range is the important one to me. And, it is supposed to require no modifications. As soon as I get the various bits and pieces made, I'll try to document the whole process in pictures. I know, I suck at that! Always run short of time and forget to take the pictures! I'll try to do better on this one, Vinny! More pics to follow (we hope!)...