Frame Swap Question

[SunSoaked]

Anybody swapped a frame from a "70's (assuming 73-79 era) truck underneath a 67-72 body?

I ran across a 3/4 frame (complete/rolling) for cheap and am seriously rethinking my current M1008/69 K10 hybrid setup.

It appears the rear shocks mount outside the frame rails-perfect for my rear tank conversion. I know its 2WD but, swapping the front spring mounts from my D60 isn't that hard, I have already done it on my current frame.

I'm regretting not using the M1008 frame I pulled the axles/springs from.

Appreciate the feedback and would really like to hear from somebody who has actually done or seen it done.

[snj8198]

I've ran across a few threads on the subject over the years but I dont remember the specifics. IIRC, differences ranged with the rise and fall of the frame in the box area as well as the rear body mount pads being raised? I don't remember if there was length difference. Most seemed to come to the conclusion that it wasn't worth the swap.

Without a lift or hoist to easily set the cab and bed i can see why a guy would want to gather as much info as possible prior to attempting the swap. What a pain.

Good luck!

[SunSoaked]

Thanks Steve.
Comparing photos of the frames, it looks like you say, a difference in the rail height on the front of the bed. The 69 has two pairs of brackets on top of the rails, whereas the later looks like the bed sits directly on the frame. That part shouldn't be a big deal as long as the cab can line up with the bed and the front mounts. BTW, I have concocted a A-frame setup where I can lift the cab or bed off the frame with an overhead manual hoist, so I'm ok there.

Originally Posted by snj8198

I've ran across a few threads on the subject over the years but I dont remember the specifics. IIRC, differences ranged with the rise and fall of the frame in the box area as well as the rear body mount pads being raised? I don't remember if there was length difference. Most seemed to come to the conclusion that it wasn't worth the swap.

Without a lift or hoist to easily set the cab and bed i can see why a guy would want to gather as much info as possible prior to attempting the swap. What a pain.

Good luck!

[snj8198]

BTW, I have concocted a A-frame setup where I can lift the cab or bed off the frame with an overhead manual hoist, so I'm ok there.

Good deal! The older I get the harder it is to persuade the four fat friends to help lift the cab. Dont get me wrong, they still pile down the pizza and beer... but that's usually all the further they get.

[70custom20]

I believe the wheelbase difference is 127" for the '67-'72 frames, and the '73-'87 frames have a wheelbase of 131". As for the overall length of the frame, I'm not sure if they're the same. I guess your best bet would be to try to mock up the early cab, front clip and bed on the newer frame and see where everything starts to fall.

[ryanroo]

why no love for the OE frame?

[SunSoaked]

Ryanroo-

Lol,

I just question whether a 69 1/2 ton frame will be reliable given that I have adapted M1008 springs/14bolt-dana 60 and a 454 to it. I don't plan to "abuse" it, but once I put it together I know I'll never want to take it apart again.

I'm considering boxing the 69 frame and adding an additional cross brace or two.

What say you?

[obijuan]

I have beat the hell out of my k5 frame. If you just plan to work your truck like a normal person the oe frame is fine. Even as is.

I buckled my front frame last year just forward of the firewall. Big block and tons of low gear with tires off the ground alot. Pretty sure you will be ok.

['63GENIII]

A few years ago while landscaping the backyard, I had to get a pallet of concrete and the Kubota up to the house. 56 - 80# bags in the box and a BX 25 in a small tandem axle dump trailer behind it. That 20 mile trip broke both motor mounts and I think it was the last nail in the coffin for the TH400. Although it was WAY over weight and riding the overloads the whole time, the skinny little K10 frame held up fine. I think that the frames got progressively bigger as the years went on. I would think that you have nothing to worry about unless you're jumping your rig or just being flat out abusive. All bets are off at that point anyway.

[ryanroo]

I agree. The factory frame for the body is the easier thing. It's going to be way easier than moving everything around to do the frame swap. If you felt like boxing that is cool too, but it will most likely hold out just fine for anything you could ask out of the truck. These trucks have been built into pulling trucks and generally beaten for years and rarely have frame issues. I am an advocate of boxing if the circumstances call for it, but if the oe frame cannot be modified to sit the next step is fabricating a frame in my book. Frame swaps generally always look funky or downright sketch

[snj8198]

Boxing is cool. If not, I like the idea of at least reinforcing some weak points based on the build and use of the rig and definitely hit the typical weak spots like around the steering box and front crossmember. Add a custom trans cross member that gussets out a little more, one both fore and aft of a relocated gas tank, then a custom front and rear bumper and i think you'll have it covered pretty good. Course a well mounted flatbed could act as one big gusset for the rear! A mere 6-7,000 lbs later you're alright! hahaha, now about that diesel swap...

[RPBurris]

I have a 69 on a 78 frame done by the previous owner. If you have already gone through the work of adding a dana 60 to the front then I see no reason to swap frames as previous posts have said. That being said, previous posts area also correct indicating a body lift for the cab is needed to align the cab to the bed elevation. There are some dimensional challenges as well with the wheel base. Either way a big block, 14 bolt and D60 its gonna be fun.