^ Agreed. Don't ever put a used tranny in unless you KNOW it has been rebuilt. It is a waste of time and money as it may have to come out again in 20k miles when reverse goes out. Rebuild your own or nothing!
my 2c.
I have a DIY for removal up to the B3 bands if it helps you at all at my site.
http://w124-zone.com/?p=130