I may have a O.D. crossmember around here somewhere. I cant remember if you have a MIG or not, but its possible to cobb up a normal crossmember to fit between the gearbox and overdrive. It mounts in the same holes on the frame though. Only the AT's use the rear set. If you need to have a drive shaft made and you don't mind a trip to Winchester, I reccomend G L Dunn. (www.gldunn.com) I've had them make up several custom drive shafts for me, and they could put the large front yolk on the small shaft, etc. I seriously doubt you'll have reliabilty issues with the OD unit, after all, I rallycrossed my street car for 5 years, and never broke the shaft that extends into the OD unit. Just push the clutch in when you engage the unit and there will be no scattered linings or damaged bits. :)
Sven is still ill, I think I need to borrow that diagnostic thingy you have (if you still have it...) at the next track day.