Nv3500 to Nv4500 Transmission Swap

I have a 99 chevy 1\2 to 4x4 4.8L V8. Currently it has 164000 mi and I have abused the fire out of it. It has 305\70\16 all terrain tires at the moment. I had 315\75\16 But started breaking stuff. Shortly after putting the big tires on it I shattered the rear end. I replaced it with a Ford 9 in. Not long after that that transmission went, broke second gear. It had to be rebuilt twice because the guy I had rebuilt it didnt have a clue. Even now the transmission isnt right. I want to swap the the stock Nv3500 to a Nv4500. Anyone have any idea what is needed. Will my transfer case hook up (mine is a manual shift transfer case)? Just looking for ideas Thanks in advance. Jeremy  

What you need to do is to regear that axles here duh.... You are running big tires with tall gears and raising cane with tranny. You could swap tranny  (you would need to change bellhousing too) but then Tcase may break next. It would be cheaper in long run (and truck would run a lot better to) if you install some 4.56 or 4.88 gears in it. Do this and stock tranny type will do fine and so will clutch. You need to fix the cause not the symptoms. BTW, it is a shame that you did not wasp in a GM 14 bolt 9.5 SF axle. It would have been a bolt in and I would place it slightly above a 9 inch in torque capacity and well above it in load capacity as 9 inchers are two ton load capacity at most and all 9.5 are three ton load rated.  

The 9 in swap  was pretty much a bolt on application. When I swaped the axle I went from the stock 3:73 to a 4:11 front and rear. Since this truck is a daily driver I didnt want to go any lower. The reason I went with the 9 was because I bought a old ford truck with matching font and rear axles the front is what I was told would work, and is soon to go in, and bought the whole truck for less than I could have bought a 14 bolt rear end. My transfer case is a np 203 aluminum case. The truck I bought has a np 205 cast iron case. I had planed when I did the transmission swap to swap the transfer case too. I know that when i do the solid axle swap in the front my transfer case is going to have to adapted so why not adapt the heaver case.  

A 4.10 with 305 and OD is too tall even for a daily driver. OD makes your effective gear ratio around 3 to 1 which is tall for 305 or 315's. A 4.10 would be a fair compromise gear for a a non OD tranny. Many are just hung up on going deeper than 4.10, even with bigger tires and OD trannies which is kinda silly. Also, never seen a 203 with a Aluminum case but I have seen a few 80 model year 205's that were.  Also, while some are crazy about 205's today there are better solutions and your truck should have a NP241 or 242. On a SAS conversion, just use a Ford front axle (stay far away from 94 to 2002 dodge front axles including D60's because of notched and weakened axle tube) and keep Tcase. It will live just fine if you properly gear axles for tire size and change fluid in it every 25 or 30 K miles (more often if in mud and water) Newer Tcase has a stronger and quieter planatary reduction unit that is also deeper in low range too. I feel that today, the need for a 205 is over rated because with modern OD trannies, deep axle gears and deep low ranges in new Tcase you can build some nice packages. Low range in meant to crawl slow, not to overcome improper tire size/axle ratio combo's.  

Well back to the transmission. The one I have has been rebuilt twice. The first time it went down I chiped a gear on the countershaft. So I took it out and sent it to someone I thought would do it right. I got it back and drove it for about 200 mi and the retainer holding the read bearing on the main shaft either wasnt there or broke and droped the gears in the case. I took it back to him and he did better this time although I cant shift into second gear properly like the sycronizer is shot. So bacialy im tired of messing with this transmission.  

I understand you frustration with tranny but I beleive I would look for a late model NV3500 in a bone yard and use it. I think yours is kinda screwed up by rebuilder and needs to be retired. A 3500 is not a bad tranny and is a MD unit. I still think you would be time, more and performance ahead if you used another 3500 and maybe regeared too. With 4500 you will have to change bellhousing and you will have to us a 96 and later GM 4500 because it will match bolt pattern on bellhousings that bolt to that series engine. Stay away from Dodge 4500 because spline is wrong on output shaft. Also Dodge 4500's also have 5th gear retainer issue on 99 and earlier ones.