Geoff Weeks

Not up on the newer stuff, but I know Meritor (Rockwell) made some double reduction units. There are two different capacities you need to consider, one is the housing and brake capacity and the other is the torque/reduction needed to move that. The double reduction were built like a standard front of a tandem with a high input and a bull gear on the pinion, but differed in that the drive ratio wasn't 1:1 from the input to the bullgear on the pinon. housing and brakes were higher capacity, allowing to carry more weight.

The switch allows you to quickly test that both are working, You should see an RPM drop when firing on only one, often around 50 rpm. Start on both, flip to one, then the other, to check and then back to both.

It could be as simple as one module on the bus not "powering up".

Canbus problems and digital stuff in general is not my strong suit. However, there are people with video's on the net that can help. It would seam, and I can be wrong, that something is bring down the bus. I think the way to test is resistance across the high and low canbus lines. If it is off, then start un plugging (disconnecting) modules until the one that is causing the bus to go down is removed. Again, I am very weak on this subject, but with multiple comm errors it seams to point this way. What you don't want to do is start replacing modules trying to hit the right one, that can get very pricey and takes longer than finding the one that is causing the buss errors.

If you are removing the ground, but leaving the + connected, then you will see a voltage between the frame and the - side of the battery. Esp if measuring with a digital voltmeter. The question is: are you seeing a draw on the batteries when everything is shut off?

Paul, I'm embarrassed to admit I learned that one very late in life from someone else, but it does work, at least on the ones I tried it on.

Ken, I wouldn't say it was easy (esp in stainless steel) but is doable by someone who can flare and braze. If you have your old one to use as a pattern, you'll not need a drawing.

What I was looking for, was if there was battery voltage at the output stud. A test light is simple and easy to use for that. I wasn't concerned about regulator settings, as these type are fixed. either it charges to the set voltage or it doesn't. Another quick check you can do with the engine running is hold a small piece of steel close to the rear bearing, (A steel key ring will do) and if it is attracted to the alternator, you know the rotor field is energized. Once you know it is charging but have other problems a voltmeter is handy to have. A test light is quick and visual to see from a distance and almost impossible to mis-read. It will not tell the voltage, although if you "know your light" you can make an educated guess, but for work/doesn't work determinations it is a useful and rugged tool to have in your tool box. I wouldn't carry my Simpson meter with me in the truck, but I can diagnose most simple electrical faults with a testlight.

Here is my repair.

I don't know what the MH one looks like, but for my cabovers I made a new tube from 1/2" stainless tubing. length is the critical dimension to get right. On mine the bottom end was a compression fitting and the top end was a bell mouth to accept the "stopper" end of the dipstick, it was a separate piece from the tube itself, and was brazed on to the tube, I heated, removed from the old tube and brazed to the new. Stainless tube is hard to bend, you could use plain steel tube, which is easier to bend. Trick to bend tubeing: make the tube longer than it needs to be by an inch or more. flare both ends with a flaring tool, after installing(temporary) flare nuts. cap off one end and fill the tube full of "sugar sand" tapping several times to make sure it is well packed, then install the other cap. With the tube packed with sand, ends capped off, bends can be made without kinking it. If you try and make too tight a bend you can still split it, but most bends can be made easily. When bent to fit, cut to length blow and wash any sand residue out of the tube, and braze on the bellmouth!

I'm glad to help/

The type I think is supposed to have is what I have heard termed "vari-rate" spring pack, with a main pack and an aux pack above it, the top leaf on the main has the eye on one end to take the torque load. Very common single rear suspension. edit: may not be the top leaf, but one of the leaves in the main pack has the eye on one end.

Yeah,I saw the spring and thought "what the heck is going on here" but don't know Macks all that well, and don't claim to have seen everything so didn't say anything.

This ad lists a bunch of interchange part numbers which may help in your search: https://kuwait.whizzcart.com/product/19384513/new-diode-trio-compatible-with-1a-leece-neville-79021-33-500-l79027-l79027hd-505202-l79027hd-1-33-500-1-l79027-1-171-16000/ I looked up 79021 and 79027 on my search.

Diode trio and connection marked in black https://www.ebay.com/itm/302551471197