When someone advertises something for a tri-five it is generally for a 55-57 car. They look similar physically but the truck mount positions are different. A bellhousing from a 55-59 V-8 and 63-67 V-8 and 6 cylinder trucks will work with a SM420 transmission. (60-62 use a hyd clutch slave cyl and are different). A 68 to 72 truck bellhousing would have the larger hole used for an SM465.
Fred
