The easiest way to do it would be to buy a running K5, remove the body, and put the Caddy body on it. But check the wheelbase first. K5s are pretty short. Older Cadillacs, not so much. You might need a chassis from a pickup instead.

 

Welcome. If I were to build a 4x4 cadillac, I'd use an escalade chassis. That way it's all caddy. Who could possibly be bothered by that?

Dang, now I want one.

 

I came across a late 80s monte carlo jacked up on massive mudders, and by God it was beautiful. When I lived up north, my buddies dad had an el camino jacked with monster mudders on it. Wish I had money before I moved south. He was trying to sell it when I lived there... about 14 years ago lol.

 

K5 is the go to chassis for body swaps because it's shorter than your average full-size so it fits car body's better...But still full size strength and solid front axle.

I'd say your buddy is right, and a k5 is your best bet. Find a running driving one with a toasted body(readily available in the north east since they are just about all rotted out) I've found them for between 5-800 bucks in running driving condition, but with shot bodys

 

There used to be an AMC Eagle wagon that was similarly 'jacked up' in a town I grew up in.

Rather have the Camino.