The early 336 V8 (engine serial number less than 336035000) used '58 Pontiac 370 crankshaft dimensions while the late 336 V8 (engine serial 336 035001 and up) used '59 Pontiac 389 dimensions. Never heard of a "mid 336".
Picture shows the location of the engine serial number on the passenger's side of the engine.
Last edited by Bill Hanlon; 01/29/202212:11 AM.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12 '52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
