I've seen a parts interchange book that would list exactly which frames interchange. I don't have a copy but think I saw it at Barnes and Nobel a year or two ago.

Unless you can replace the existing frame with an exact match you are likely to be frabricating mounts and adapting things to make this work.

We can't see what your frame guy is looking at, but any 40 year old frame is going to need work and bushings and springs are likely going to need replacing. The further your replacement frame is from being a '63 the more you are likely to need to adapt.

1963 was the first year for the front suspension design stock on your truck. That IFS was used on pickups through 1987 and a few years more on Suburbans. If you must swap frame my inclination would be to broaden the search and find the best donor frame you can up to '87, knowing even the newest of them is 20 years old and is likely to need some work.

In any case you likely will face mount fabrication and such and this will be a lot of work.

I don't know why your frame guy is condemning your original frame, but as I think of the work involved I'd sure think hard about fixing versus replacing.

1955 1st GMC Suburban | 1954 GMC 250 trailer puller project | 1954 GMC 250 Hydra-Matic | 1954 Chevy 3100 . 1947 Chevy COE | and more...
It's true. I really don't do anything but browse the Internet looking for trouble...