ADSITCO has a horrible reputation. Avoid them at all costs. Period. There used to be a detailed thread about those
thieves, but I can't find it at the moment. Here's some light reading in the meantime....
http://www.ai.org/judiciary/opinions/pdf/10160704jgb.pdf
http://www.peachparts.com/shopforum/showpost.php?p=1767881&postcount=8
http://www.peachparts.com/shopforum/showthread.php?t=227283
http://www.peachparts.com/shopforum/showthread.php?t=116464 (check out post #16 also, on page 2)
I'd get the tranny done by Jonathan at Blue Ridge MB, or by Peter Schmid. Or your local MB dealer. $5k is a ripoff, though. BTW, I don't think anyone "rebuilds" torque converters. They just clean & test old ones, and offer a warranty on them. It's not an item that can be disassembled and repaired.