Inspection of a 904 torqueflite

There was something of an overdrive 904 with lock up known as the A-500 loosely based on the A999 torqueflite (HD904 with extra clutch discs and lower gear sets). Used in the nineties in Dakotas and the like. There are articles here on forum about adapting one into an a body and U.S. car tool carries a crossmember if You don’t want to modify your existing unit. That is if you really want to get into the overdrive deal. A 200R4 lockup GM transmission seems to be a more popular option, but I have yet to research the topic thoroughly enough to know why.