I started out building a 1964 GMC pickup for our toad. The rearend is from a 1984 Suburban as is the 700r4 automatic transmission. I had a Remco disconnect installed to make it towable. Lot's of dealers said it couldn't be done. The trick is to find a dealer that can actually build stuff as opposed to just install stuff. I lucked out and found such a dealer just South of Fort Worth, TX. MAC'S PERFORMANCE for Cummins, Duramax, Powerstroke, R.V.'s and Hotrods - Main Page
you need to use IE for their site. Ask to speak with Mac. They did me a first class job! I would be confident in saying they could make virtually anything towable if you have the time to wait on it.
Unfortunately the GMC is setting in a storage shed waiting for me to finish it. I will get it done someday, we just ended up getting on the road sooner than we expected to.