GM automatics and 4 wheel drive

Old 10-22-2011, 08:06 PM
  #1  
ogles824
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Default GM automatics and 4 wheel drive

We have a 1988 Chevy K5 Blazer that is about to under go a motor change
My son and I are about to do a major motor transformation in either an LS based engine with a 4L60 automatic which we plan to buy a whole 4x4 trans if we go that route. We are also looking at going in the total opposite direction with an "old skool" carbed 383 motor with a tunnel ram set up with either a Turbo 350 or 400 trans. My question is can I buy a regular 2 WD trans and remove the tail shaft and bolt the transfer case from the 700R4 directly to one of thse transmissions or do I need to find a whole TH 350 OR 400 4X4 trans and just build it? I'm wanting to buy a TCI street fighter or similar trans that will support about 425 HP and add the transfer case to it if I can.
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Old 10-23-2011, 09:00 AM
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coloradoracerguy
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You can take any th400 or th350 trans and run it in a 4x4. You were right on changing the output shaft, and you'll also need the correct adaptor for the t-case you plan to run. The t-case will also need the correct input shaft for the trans you plan to run, as they are not all the same. My two favorite combos are a SM465 four speed manual with a NP205 case. Bullet proof and pretty indestructable. For an automatic setup, I prefer the th400 with the NP 205. Also bullet proof and nearly indestructable. All going to depend on what transfer case you plan to run and what trans you decide on. For an auto, I'd lean heavily towards the th400, but that's just my opinion.
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Old 02-14-2012, 10:13 PM
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olds48
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The correct adapters to mount a transfer case to an auto can be hard to find and are very expensive to but new. You could always use a divorced transfer. Plus,the fact that they mount a little further back than a tranny mounted transfer gives you more length for your front driveshaft which can be really helpful when the truck is lifted and you have u-joint angle issues.

x2 on the 205's. I dont think they can be broke!
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Old 02-15-2012, 12:53 PM
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TheRabbit
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You can get the adapters for about $200- $250. A lot of machine shops will make them for you cheaper than you can order one.

The 208 are not as bad as people say they are, but the 205 is a lot tougher. I've run over 1,200hp through one with a trans brake set on 5,200.
208's are 2.61 low gear and the 205's are 1.98 in if that matter s to you.
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Old 02-15-2012, 10:03 PM
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olds48
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Rabbit,where are you finding adapters for that price? Last time I looked i couldn't find anything cheaper than about $450. And factory 4wd parts out of a junk yard pretty much don't exist around my parts. I got a '72 C20 that I cant decide to convert to 4wd or slam it. So far this has been the deciding factor. I did score a divorced 205 out of a junk yard for $50 ( right after i said those parts weren't around here ops: ). Been thinking of using that behind a 700r4. Concerned about towing an enclosed with a 700r4,though.

SORRY FOR THE HI_JACK! Please forgive me ops:
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Old 02-16-2012, 06:17 AM
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You're not gonna find one advertised by a manufacture cheap. You're gonna have to get a local machine shop to make one for you. And even if you do that you will need to find a shop that has already made some and know what you need or they will charge you a ton.

If you can't find somebody call Scott at racinginthedirt. Super good guy and will make anything you need. He deals in custom made 4 wheel drive parts.
http://racinginthedirt.com/

He used to keep an add in the mud racers section on RJ, but I didn't see it this morning.

If you do call tell him I sent you.
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