2wd converted to 4wd.

[79 blue monster]

I have a question on my 4wd conversion. Started out as a 79 gmc c20 and now a k20. I have the complete front end rebuilt and under the truck already, but one thing is holding me up yet... the transfercase. Do I need to cut my floor out to fit the transfercase under my 2wd cab or will it fit fine? Shims maybe? I've heard both yes and no. So I'm trying to get a straight answer.

[craig113]

You can either swap out hump from 2 to 4 to give you the extra 2 inches needed to clear the transfer. Or add a 2 inch body lift.

[andrewmp6]

Swapping the trans tunnel hump is easier then a body lift tho.Only hole you should have to cut is for the t case shifter that should be it.What trans and t case are you going to run with it?

[79 blue monster]

It's a pontiac th400. And that's the other question I have. Which transfercase do I need? I have auto locking hubs in the front.

[slotard]

There are lots of options, and what works best depends somewhat on your plans. If it's getting big tires and big power, strength is more important than if you're staying fairly small.

What're your plans for tire size, and how will you be using it?

[79 blue monster]

I want it to be able to hold up against pretty much anything, but I'm gonna mostly street drive it. It's more of a show truck. It's 4in lift with 35's I pan on going a little bigger lift though.

[slotard]

The NP205 is one of the stronger TCs available. http://www.fourwheeler.com/how-to/tr...ransfer-cases/ has a comparison of a bunch of options that they like.

What front axle is that? Why a Pontiac TH400? Engine?

[79 blue monster]

I have a 500ci caddy motor swapped into it. So I should go with a 205?

[slotard]

The 205 is strong, but some of the other cases have a lower ratio low range (205 is only 2:1). If you're sticking to 35s and not hammering it hard in the rocks it's probably overkill.

[79 blue monster]

I'm running 4:11 gears front and rear

[slotard]

I can't tell, what axle is that? What're you doing for steering?

[79 blue monster]

It's just a GM 10 bolt. And just the stock steering for now

[slotard]

I'd highly suggest crossover steering, it'll work a lot better (especially with any lift).

[84chevyguyid]

I did a 2 to 4 wheel drive swap to my crew cab and found a bolt in 4x4 hump, cut the 2w drive one out and bolted the 4x4 one in. Also came with the transfer case shifter so that saved alot of work. My tcase is a 208 so probably a different shifter than you will be looking for.

[andrewmp6]

Is the turbo 400 changed over to a 4x4 tailshaft or is it still got the rwd one?As far as which t case a np205 is the best oem one to use and they came stock in the 1 ton square body trucks on a turbo 400.If you can find one in a junkyard grab the trans if yours ain't changed over to a 4x4 one t case shifter the crossmember and maybe the rear driveshaft.As far as the 10 bolt with 35s if your easy on it should be ok,If your looking for more of a hardcore off road truck i would change it to a dana 60.As far as rear end 12 bolt would be the smallest i would use and with that kinda power and tire size 14 bolt full float would take anything you can throw at it.

[79 blue monster]

I have a 14 bolt in the rear. The shaft is still the 2wd. I have to get a 4wd shaft that matches my t case I want. As far as the front axle holding up, I'm just road driving, and maybe off road trail driving. Not mudding, jumping or rock climbing. The truck is to clean to beat the crap out of it.

[andrewmp6]

Hit up the junkyard and find a turbo400 np205 if you can it will make your swap easier then trying to piece it together.The np203 and np205 are iron case and look kinda a like.To tell them apart http://offroaddesign.com/catalog/Tra...ID%20Guide.htm If the t case has a aluminum case on it its a np208 or np241 you don't want those.