The bell housings are different. The original engine/trans combination the mounts were on the front of the engine and on the bellhousing, none under the transmission. The later engines (230/250/292) had side mounts and the 292 is different in that the mount on the passenger side is more to the front of the motor. However if you can find a bellhousing from a later 6cyl or v8 truck, it will bolt to the original crossmember and you will be ok.


Tommy
59 apache 1/2t
261 short stepside