d8 2u transmission

You are correct, there is both a transmission gear and case change at s/n 2U21513. To do a gear swap you need to find compatible units. With the right interchange units it's still quite a job but doable.

I think that you will find that the very late serial number D8 2U tractors are basically the same as a 13A series, maybe look for compatible parts or complete transmission from a 13A, the high serial number 2U will be the much better tractor to restore and keep.

I didn't compare all the gear sets but the 8F4489 case change at 2U21513 is good through the end of 2U production and all of the 13A's.

Can you expand on the gear sets and case changes? If I am understanding what you are saying..... The gears might be a different ratio from 21513 to the end of the 2u production vs what a 13a would have. But 13a gears will definitely be a direct swap into my 21902? If so, I don't mind different ratios at all.

What would be the estimated time to pull a good set of gears from a trans, pull the bad set from 21902 and put the "new" ones in? Just looking for an estimate as I have no idea.

Yes, there are three different ratio sets of gears between 2U2153 and the end of 13A production, all on the same case. As long as you stay within the set your good for interchange.

I really don't know on the time but I'd guess it would keep a couple of guys busy for three to five days. Also depends on what they run into as these machines are 60+ years old.

The shop is going thru the books and doing a part search to see what is out there for replacement parts. Worst case if there is nothing out there and I can't come up with any used parts I have an idea..... Since only 1 and 2 forward gears are out, what about just running it that way. I spent a few hours on 17234 today and did almost all of my work in 3rd gear. What are my chances that the transmission would stay the way it is now? Is it likely that more gears will go out? It appears that a previous owner ran it with little or no oil in the transmission. I think if I use some common sense and don't abuse the clutch I could use 21902 for dirtwork only and can get a lot of use out of it. What do you think?

I was told engine has to come out so you can have room to pull that massive front cover complete with the gearshafts out of the chassis case on a 2u to work on the gearbox ?? Knowing that its all one case I believe it; but has anyone here actually rebuilt a later 2U or 13A gearbox ??
just a question for curious minds ???