C to K conversion or extend frame?

[pseudomike]

Hey guys, I have a friend that is interested in the crew cab I am parting out. He has a K30 reg cab dually that is really in need of a cab. He would like to make a crew cab dually 4wd out of the two. The one I have is only 2wd. He was thinking he would swap his gear and brackets to the 2wd frame. Having done that same thing many moons ago on a C10 I though it would be easier for him to cut and extend his frame under the cab using frame sections from the 2wd then drop the 2wd cab on his frame. What do you guys think would be the better option? I know he has to modify the transmission hump either way.

 

[KansasTwister]

I would just bolt the 4x4 stuff onto the 4x4 frame, less welding to think about imho. It can be done either way, just i think bolting the 4x4 hangers on the 2wd frame will be the best, as long as the frames are both 73-80 or 81-91 (solid axle, of course)

 

[pseudomike]

His truck is 4wd so no swapping of hangers needed. I was thinking that swapping the stuff to the 2wd frame is a lot of rivet grinding and hole drilling. I also remember from mine that I had to custom fabricate a motor mount cross member and front cross member because the frame and the cross members are different up front. perhaps it is the same in the 30 series, not sure. IIRC my 2wd frame was like 1" shorter in the motor area.

His truck is not a crew cab it is a regular cab so just to clarify he either needs to extend his frame or convert the 2wd crew cab frame I have to 4wd using brakets etc off his frame. His truck is an '86 the crew cab is an '88 so same vintage.

 

[pseudomike]

How about cutting the frame under the cab and using the rear section of the crew cab 2wd frame? That way there would only be one cut?

 

[str8axle55]

I would think converting the 2wd over to 4wd would be much less work. I have thought about this also, but I want a CCSB, so I`m going to need to cut. I might know of a 4wd reg cab.

 

[pseudomike]

It's hard to say, I guess it depends how good you and your welder do together. Converting to 4wd is definitely no walk in the park. Aside from swapping the entire drive train over (exhaust, motor, tranny, so on so on) you have to grind and pound about 70 rivets out, drill all rivet holes to 7/16" and re-bolt brackets, drill holes for shackle hangers, and fabricate a new cross member for the motor mounts.

Cut frame seems easy. Measure four times, cut, weld, grind, fish plate, weld, drop cab on, done. I'd don't know, I can cut and weld pretty fast. Once the cab is off it's a cake walk to get to. Only concern would be strength and I think this has been well covered before. I have seen it done more than once without failure so I am pretty confident in the attack to take.