Hi Gophergunner. I have been reading the posts here and may have some help for you with the trans. part numbers for the 4-53. I have a 53 series SAE #3 housing too if you are interested. It is the housing that has the round opening for a trans with the SAE bolt pattern with 17 inch bolt to bolt pattern. The adapter adapts the rear housing of the engine to a standard GM bell housing to bolt up to a 4 bolt manual transmission with clutch and all. Not sure if the part numbers are valid anymore though. The adapter uses the standard rear trans mount across the frame. Good luck!