If you go Auto Trans you will need to change the motor mount set-up.
The factory stock V8 used the same type mounts as the 6-cylinders (2 at the front and 2 at the bellhousing). Installing a newer auto trans you need to go to the 3-point mount system (2 at the engine side and 1 at the trans tailshaft).
If you stay with the factory 4-speed all you need is the Truck V8 bellhousing and the 55-59 V8 motor mount kit sold by all of the vendors. This kit has 2 new brackets that bolt to the front crossmember moving the mount points back a few inches due to the V8 being shorter than the 6-cylinder. This is a easy conversion.
Hope this helps,
Mike B
