Hey guys, don't forget about the NP-540-542 transmission series. They are a close ratio 4 speed w/ a granny gear, much more useful than an SM-420, SM-465, NP-435, etc, especially if you haul a load.
They came in most everything, including Ford, Studebaker, Diamond T, etc. Just 1.5 ton and larger trucks, never pickups. Obviously Chevys are the most popular. They look like an NP-435 with an aluminum top cover but have FOUR (4) shift rails-this is the only trans. w/ 4 shift rails and AL top cover. Some even came w/ OD gears (rare.)
They only came in 2WD versions, however, they are easy to adapt to 4WD. I have adapted one to a Spicer 20 transfer case (early Bronco)which I hauled loads up to 14,000 GCW behind a Buick V6 engine, and to a NP-241D (Dodge) transfer case.
Parts are readily available.
I have one in my '47 GMC(302) w/ 3.42 stock gears to get a good cruise speed.
When you look for one, don't ask for one, they won't know what you are talking about and raise the price. Just ask to get in the yard and find one and look carefully at the shift fork pins (steel) that are cast into the AL shift housing. Sometimes they get loose.
Be careful, they come in short (stock Chevy) and long input shaft varieties. You cannot always get a short input shaft for your long shaft trans. Since the short shaft varieties are getting scarce, you can put a long shaft version up against a Chevy block by getting a deep(stock) bellhousing w/ the .25" stock adapter for a GMC V6 engine and also a Chevy 366 engine. These come w/ the side crossmember mounts in the correct place.
Good luck
