2x4 To 4x4

[Hittman]

I recently acquired a very nice '71 3/4T 4x4 frame. I plan to place the body of my current '70 3/4T 2x4 4-speed on to it. My understanding is that this may not be a simple "weekend" project as not everything is a direct bolt on application. The kicker is that this frame was set up for an auto from the factory but it does come with a 4-speed, transfer case and cross member from a '69 - not installed. (My brother actually has the '69 frame but with the auto, transfer case and cross member from this '71 frame - I know strange circumstances). Yes it would be nice if we could just agree to swap frames but I want the disk brakes and he wants the auto so you see the dilema.

Anyway my brother has discovered that the cross member holes in his '69 frame are roughly 3 inches off where his auto cross member needs to be. I can only assume that my '71 frame will also be about 3 inches off in the opposite direction for my manual tranny cross member. Can any of you confirm this? I would have thought all 4x4 frames were the same or had both sets of holes popped in the frame rails. Is this just a fluke deal or were there separate frames between autos and manuals or did it change from a '69 to a '71?

I also hear that 4x4's actually had a slightly different firewall on the cabs. Apperantly there is a clearance issue with the distributor when a small block 350 is mounted in there? This info is coming from another source which I don't know so I don't know what to beleive. Can anyone confirm this? I plan to re-install my factory '70 350.

I also understand that my new exhaust for my 2x4 will not work with the 4x4 frame due to the transfer case being in the way. Do the 4x4's also have a different exhaust manifold?

Other than the tranny hump being different I can't imagine there would be any other issues. Any help from anyone would be greatly appreciated. I hope to tackle this project here in the next few weeks.

[DieselEater]

I've done this a couple times, and am doing it again currently. Like you said...the tranny hump should be the only major problem...(sawsall). The rest can be dealt with without problem. check out some pics on my sig.

A..........

[1969k10stepside]

Cab is the same with the exception of the center hump.But since your truck the body is coming from is a 4 speed it should have the bolt in high hump.The clearance issue with the firewall is on all 4wds since the motors are mounted farther back than on a 2wd.The firewall between a 2wd and 4wd is the same.The 69 had a Rockwell transfer case stock and is mounted in a different spot than the NP205 is that a 71 would have.Auto or manual the crossmember is the same and is in the same spot if it's for the same transfer case.The crossmember is also different between the 2 and you will need the one from the 69 or another 67-69 4wd.You will need the driveshafts from the 69 (or another 67-69),and you will have to move the transfer case crossmember,and torque bracket forward.You will also need the frame bracket for the z-bar.If he doesn't have the drivetrain in the 69 frame yet he will have to do the same stuff but backwards like using the driveshafts from the 71,using the crossmember from the 71,moving the t-case and torque bracket mount back,etc,etc.Honestly I'd convince him to swap frames and make it easier for the both of you and just swap out the front axle so you have discs.
Hope this helps.

[Hittman]

DieselEater - your Myspace site is sweet. Nice job on that puller!

1969K10Stepside - Thanks for all this info. It all makes a little more sense now as to why there is such a difference in the location. I agree that it would just make more sense to swap frames despite the fact that I would rather have the '71 with the auto...

In your opinion (or anyone else for that matter) is the 205 a better transfer case than the Rockwell? I also understand that there is a difference in the front axles in that one has open u-joints (the '71 I believe) while the other is sealed ('69?) on both ends. I can only assume the design changes for the '71 were all improvements not to mention the disks.

Another thing I am not sure about yet is the axle ratios. Being that they are both 3/4 ton frames is it safe to assume they are all 4:10's or were there other options?

And again regarding the exhaust - will we need different headers/manifolds for the 4x4 vs. our existing 2x4?

Thanks again guys!

[1969k10stepside]

Is the 205 better? Well,they are about the same strength/durability wise in my opinion.The Rockwell was used for only a few years though while the 205 was used for a long time so it's easier to get used parts,and they are usually cheaper and a rebuild kit for a Rockwell is usually higher than a 205 rebuild kit.Some people here have had bad luck with their Rockwells,while others don't.The front axle is the same axle (Dana 44) but in 70 they transitioned from a closed knuckle to a open knuckle.They kept the drums till 71 though when they went to discs.Turning is better with the open knuckle axle.On the exhaust,some manifolds dumped straight down while others were angled.I think the ones on the 4wd dump straight down,don't remember.A 4spd 2wd may have the right manifolds.I don't remember much on the stock manifolds...

[hilbilly]

i know the ins & outs of the 205 so of course I like it better. if you not going to abuse it, keep the rockwell. like 1969k10stepside said, the 205's are cheeper to fix. that really up to you.
check the gears don't assume anything. on old trucks you never know who's been in 'em