Always heard nothing but horror stories on Jasper stuff so id shy away from them. Beermill's deal sounds pretty sweet id take him up on that offer. Most places will cahrge you a diag fee of around $100.
I work at a transmission shop and in my opinion Jasper is the best rebuilder hands down. I have personally installed hundreds of their products from front diffs,engines,trannys,transfer cases...ect and we have had like maybe 2 problems and jasper made it right before it left our shop. I'm not saying that you will never have a problem because after all they are built by humans. I would go as far to say that they rebuild a product better than its made from the factory...the are always installing improved parts and their R&D is excellent....JMO