Alexandre: Bellhousing on all Chevy six 216, 235, and 261 is same bolt pattern from 37 thru 63. The flywheel and crankshaft bolt pattern is the same from 41 thru 63.
All 41 thru 54 flywheels use the wide 139 tooth ring gear and six volt starter.
All 55 thru 63 flywheels use the narrow 162 tooth ring gear and twelve volt starter.
Can't help you with GMC info, don't know! Maybe Jolly knows or can answer your questions. Jolly is the BB resident GMC man.
What do you say Jolly?
Think Chevy! :confused:
