For specific GMC info, try this.

Same guy runs a GMC specific forum here, but it has much less traffic than the StoveBolt site. Also, you need to join to access.

I don't have a lot of Canadian GMC info, but what I have shows either Chevy (6 cylinder) or Buick (V8) engines in the late 50s.

As Jerry says. the GMC engine size is the first 3 digits of the engine serial number located as shown in the attached picture.
Attachments
6CylSerial.jpg (38.84 KB, 166 downloads)

Last edited by Bill Hanlon; 01/22/2025 12:00 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.