Awsome thread, go out there and bang some gears and keep us updated.
Ya I dont think a 4" will fit either, Id like to see a one piece made. But It would only be worth spending the $$ if it was alittle lighter then stock.I honestly don't know, the 4" is a very tight fit and the rear needs to be held much tighter then it is with the factory set up.. (which is another thread/issue)
I can tell you the mustang which also has the slip sleeve dilema is around 690, but the caddy has the rzeppa end to deal with and the fixed end tripod at the trans...that's going to add to the cost, and then the hanger structure is another issue to lose
If you guy's ever blow up your trans, lose that particular style t56 and get the slip yoke version.
The shaft can be so much lighter with the slip yoke version over the fixed style shaft
Every pound is equal to 20 lbs carrying in the driveline.. so losing 10 lbs in the driveline is like losing 200 lbs of carrying weight.