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View Full Version : Chevy T case Experts Wanted



90guy
10-26-2013, 06:27 PM
Well guys I have a 76 Chevy Cheyenne k10 full time 4wd. Well to say the guy must have knew something was up with it. So I unloaded it from the trailer and stepped on it and heard a whole bunch of noise and then lots of grinding when I am driving or with the brakes on. Does the same in reverse. Dropped the T case oil today to just see silver oil come out of it... So here is the question. My T case is garbage I do know that lol. The question is can I throw a part time Tcase on it and keep the front axle as a full time front axle? Would that work? Thanks in advance guys.
Todd

slashfan7964
10-26-2013, 07:11 PM
What transfer case is it? I'd be willing to bet it's an NP something. You can identify it by crawling under it and looking at the casting number on the case itself, both front and back. There will usually will be some sort of tag with the number/model stamped on it. If it's rusted out, this may prove difficult.

My Ford has a NP208 transfer case. It has manual locking hubs up front. As long as you have the hubs engaged and it's in 4 Low or 4 High, you will have 4WD, and can use it like a full time T case. I actually prefer part time because then I can drive it in 2WD daily with less stress on the drivetrain and you'll see an increase in fuel economy, as well as having more of a gear range to pick from. If you have it in 4WD but the hubs aren't locked, it's pointless because then your wasting power. The rear wheels will be getting less power and half of that (depending on your torque split) will be going through the front differential without the half shafts turning, therefore not turning the front wheels. So as I said, as long as the front wheels are locked, you can run it that way. Another benefit to manual locking hubs is that you can lock one side and not the other to provide maximum traction to the side that's stuck. At the same time, you can drive with the hubs locked all the time in 2WD, so you don't have to get out and lock them when you engage 4WD. You simply have to make the change from 2 High to whatever 4WD setting you want, as well as what gear (ie automatic 1-2, D, manual 1-4 etc). Manual hubs are a good thing but aren't needed to run a part time case.


A problem you might run into though is if your front end doesn't have manual locking hubs, in which case you'll need to swap out your assembly to accept them. WARN is a good option for manual locking hubs. Hopefully your differentials have some sort of LSD system or locked differentials. Open's are fine for normal driving but aren't too great off road.

If you change them, there is also a chance the driveshafts might need to be changed since the yokes/u-joints will likely not be compatible and the length of each might be slightly off. This depends on your choice though. There is many options out there, so have a look around.

If it's a full time without any kind of 4WD shifter, you may need to cut a hole in the floor to run a shifter with a part time system. You'll also need to buy a boot to cover the hole in the floor and purchase the linkage that you need. It's a straight forward swap, but it will cost you a bit more and you'll need to have the cash on hand unless you have the parts lying around the house.

Personally, I'd try and find a mechanical part time transfer case that allows you to engage 4WD at any speed. Some require you to be stopped or under 2mph for it to engage. Depending on what you intend to use the vehicle for, it may or may not matter. My personal choice as I said is one that allows you to engage 4WD at any speed as it makes life easier in most situations.

90guy
10-26-2013, 11:27 PM
Well got it figured out we think lol. Ok here is the scoop. My dad picked up a 76 chevy to use as parts but we have been driving it lately! haha. He picked up a 73 which he is restoring to look like his old pickup. So he called me tonight saying that his 73 has full time in it, and his first truck had lock outs on it. So it looks like in about a week we will be pulling the transfer case from his 76 aka Gene, putting that into his 73, and Taking the full time t case and putting into my 76 aka Rusty. Along with a bunch of other parts from Gene. Only problem, be a lot easier to swap the parts around from truck to truck if I trailer Rusty 5 hours one way home! Dang trucks! lol All this for a winter work rig!

slashfan7964
10-27-2013, 02:44 AM
Make sure it will accept the yokes on the driveshaft and unjoints bolt up. Driveshaft length could still be an issue unless both transfer cases are the same.

coolpool
10-27-2013, 11:13 AM
Glad you got a solution figured out. In the mean time, try to find a donor truck with a (New Process)NP205 gear drive case in it. Combine that with WARN locking hubs and you'll have a nice set up. The NP203 you have is chain driven and prone to breaking. We used that exact truck (76 Chev Full Time 4WD) in the Canadian Military and couldn't keep T-Case' in them. Not sure how much cash you want to invest in the swap but it will probably save you that in fuel in a year. And if you haven't discovered this yet, if I remember correctly you don't use gear oil in a NP203, you use 10W40.

90guy
10-27-2013, 11:54 AM
Thanks CoolPool. Yeah this truck is just my winter rig to get back and fourth from work. I bought it for $500 came factory with a 400 and it is swapped to a 350. Truck runs great transmission is a good turbo 350 in it. So basically Im going as cheap as I can to get this thing on the road back and fourth from work. Gas mileage dosent really bother me. My summer rig is an 89 Toyota celica and it makes around 35 mpg lol. But It would be nice to swap np 205 in it. Yeah I remember reading that some where that the np203 ran 10w40 in them. I just cant wait to get it on the road! I dumped the oil from it and it came out pure silver, I could play with the oil with a magnet! lol

slashfan7964
10-27-2013, 05:01 PM
I agree a 205 is a good T case. Should be easy to find

blue27
10-27-2013, 07:01 PM
mile marker made a kit to convert the 203 to part time and just add lock out hubs, save a bunch on fuel. The 205 it one of the better cases to use.

Dirtcrasher
10-29-2013, 04:55 AM
Back in the day I had a gear driven transfer case and an old rotted truck off a trail gave me a 69 axle with a locker in it!!

I sold some of it, then the guys came in the yard and stole that locker :D Thanks losers!!

I'm sure karma got him back!

That 3/4 ton truck had a 327 and I could hang with 5.0 stangs and I was running Dick Cepek 36" fun country tires and 8"s of lift. 7 mpg's but I loved the heads that turned everywhere for that truck!!

slashfan7964
10-29-2013, 07:33 AM
Back in the day I had a gear driven transfer case and an old rotted truck off a trail gave me a 69 axle with a locker in it!!

I sold some of it, then the guys came in the yard and stole that locker :D Thanks losers!!

I'm sure karma got him back!

That 3/4 ton truck had a 327 and I could hang with 5.0 stangs and I was running Dick Cepek 36" fun country tires and 8"s of lift. 7 mpg's but I loved the heads that turned everywhere for that truck!!


GRRRR lol. You're making me want to wrench on our old Ford. Granted, we plan on restoring it and are slowly buying new body panels but still. That old F250 was a fast SOB with 4WD engaged...took out my friends lightly modded '00 Mustang GT 4.6L. That was a fun race lol. Going on it's 4th engine now, its current (3rd) is a 1975 351W. Had 33s all the way around, at one point a 3 inch body lift, roll bars and lights, pipe bumpers etc. Was a beautiful truck, but got 6mpg lol. Shame it rotted out.

Pic was taken mid '90s ish before the pushbar was added with orange/black KC lights, and the roll bar was painted black. Has a custom bumper on it right now though. Baja lights are now changed to the rectangle ones and aren't hooked up anymore. Paint was fresh and all the body panels replaced. Going on tailgate number 4 and set 3 of front fenders lol.

http://i1013.photobucket.com/albums/af257/slashfan7964/scan0001_zps8025a18a.jpg

90guy
11-03-2013, 06:54 PM
Well It is getting an NP205 with lockouts put on it. Heck with this fulltime garbage!

90guy
11-03-2013, 07:07 PM
Haha thought I'd throw this up. That would be a photo of the 76 of mine. 180220