[Mark IV]

The "FT" engines often are forged cranks, but as stated have a larger diameter crank snout that can be turned down. The bottom ends are reputed to be stouter with thicker webs and some have the bosses cast in for the crossbolts.

The distributor hole is larger as the medium and heavy trucks used a cable drive tachometer that requried a larger diameter distributor shaft and thusly a larger housing diameter.