One thing to keep in mind - the Aluminum cased OD transmissions have a known problem. They use a floating countershaft, and the aluminum hole that the countershaft goes in can wallow out (due to the soft Aluminum), which will eventually cause the gears to separate and cause a major failure of the transmission. I had this happen on an Aluminum cased 833 OD that was behind my 360, and the gears literally broke into hundreds of little pieces. The only options to prevent this are to install bushings in the case for the countershaft, or to transfer everything from the Aluminum cased tranny to an Iron case.