203/205/208 t-case mumbo jumbo

[tomtuna1978]

ok so ive got a 79 k10 short bed fleet side with the 350/th350/np203 gear(dont know the rear diff 12 bolt and front diff 10 bolt gears yet). The 203 case started leaking and the rear drive bearings went out a wile ago(truck has been sitting for 3 months). so ... ive been doing a lot of reserch on these transfercases and transmissions and junk, searched until my eyes were blurry and then surched some more ! from my reserch i now understand(correct me if im wrong !) that the np203 case is pretty much only good to make a doubbler with, the np205 is THE ! good case to get, and the np208 is a decent aluminum one that will take some abuse. NOW ... i have got a 700r4 trans out of a 84 van(2wd) for free a few weeks ago(was told it was rebuilt like 5k mi. ago, but would go threw it anyways to make shure). and would like to use it for the od,as the th350 is spinning the engine at like 4000 rpm at like 65 mph now. im only going to use this truck as a fun beater/light towing/and id like it to be as reliable as i can get.here is my questions ..... how much work is it to do the doubbler with the 700 trans(i can get a 205 for 350$), do i need to get new drive shafts and re mount the trans crossmember,and how heavy will that be ?(that 203 was heavy as hell !!!) if i can get the 208 case(havent even tried to find one of those yet), will it mate up to the 2wd 700r4 trans? and what kind of trans crossmember/driveshaft mods will i be doing? and what do you guys think this will cost me? and what would you do ? should i just rebuild the 203? and live with the rest of it ? i dont want to spend a lot of money on it rite now ! but i know i got to spend somthing ! any help would be aprishiated ! sorry for the long post !!! and i think i did as much reserch as i could ! if you guys got any more info sights or threads for me, let me have it ! thanks guys !!!!!!

[MTCK]

If you get a doubler you will for sure be building a new cross member and be lengthening/shortening some driveshafts. www.offroaddesign.com has a wealth of information regarding input shaft and output shaft splines for GM transmissions and transfer cases. If it is not going to be a wheeler I wouldn't mess with the doubler. You will spend upwards of $800 just in parts to get that done, not counting the cases, crossmembers and drive shafts. For what you describe I would install the 700r4 with a 208 behind it. Not sure about the cross members but there were a ton of these square trucks 82-87 that had that combo. I don't think the 2wd trans will bolt up. New tail shaft and output shaft for sure, might be a no-go period. You will like the low first gear, overdrive and lower low range in the 208. Good luck. Oh and www.bowtieoverdrives.com has a lot of info about the GM overdrive transmissions and swaps.

[71blksuper4x4]

Beefiest transfer case that Chevy had was the np205 (gear driven). You have a np203 (chain driven). Now there are a couple different routes you could go. You could go with your th350 with a np205, but you might need the correct adaptor that mates the two together. You won't have overdrive, but it is still a very respectable combo. Another option, if you are wanting overdrive, is to use the 700r4 2wd tranny you have and find a divorced np205 transfer case out of an older Dodge, and install a small driveshaft between the transmission and transfer case. This is an ok approach, but it's one more driveshaft to make, and you will have to make several parts (shifter, linkage, 2 new crossmember- 1 for transfer and 1 for transmission) That could get costly for you in parts, labor, and time. The best approach would either be find a 4x4 700r4 transmission (post '90 are best) if you want overdrive or rebuild your th350 or find another one and buy a np205. You don't really need a np205 unless your chain is slipping in your np203. Trevor

[71blksuper4x4]

oh, and the np205 is just as heavy, if not heavier than the np203. Trevor

[tomtuna1978]

maybe ill just fix the 203 and sell the truck ...lol

[tomtuna1978]

there is a np205 here in town on cl for 400$ ... should i swoop it up ? what all do i need to change to swap it out ? the front and rear driveshafts ? will the shifter go in the same hole in the floor ?

[71blksuper4x4]

$400 seems a little steep. I have seen them anywhere from $150-300. I don't think you will need different driveshafts, but could be wrong. You will need the adaptor to bolt to your Turbo 350 trans. If you are wanting to still use your 700r4, you will need to find a divorced 205 transfer case. As far as the shifter utilizing the same hole, it will come close if it doesn't fit. Trevor

[84 400]

I found a np205 locally for 60 bux but got a different set up. You will need a 27 spline modle that bpolts to a th350 tho not the 10 spline sm465 or the 32 spline TH400 one. They are some what hard to find in the 27 spline. Also if it uses the old spicer yoke you will need to swap that fpr the flange.... The 205 is shorter because it does not have the aluminum differential cone section the np203 has. The 203 also has a lower low range then the 205.

A 203 is nice for plowing, winter driving. If your going 700r4 I would just go 208 or 241.

[tomtuna1978]

ok the guy said he would sell the 205 for 300$. but it has the slip yolk on the back. what will it take to swap it to the fixed yolk in the back ? it is for a th350 thow! he wanted 150 just for the rear driveshaft !!!

[b454rat]

That is way too much for a t-case!!! You can bolt up a 205 to a 4wd 700, need the 350/205 adapter and a spacer that goes between the tranny and adapter so you don't have to change or cut the output shaft.

And a 203 is heavier than a 205.