As far as I can tell,in trucks like 1/2 and 3/4 ton,GMC and Chevys use the same tranmissions,axles,springs,brakes,and the thickness and width of the frame rails is the same with minor differences on the front crossmember.Other than the grills,the sheetmetal is nearly identical.
That leaves the engine as the only real difference.Was the 228 GMC better than a 216 Chevy as the way trucks were used back then?Did the GMC last longer? Chevy was the truck sales leader back then even with the funky oiling system on the 216's.If the Chevy engines were inferior,they wouldn't have sold so well.Besides GMC,the flathead Mopar 6 was a reliable full oil pressure engine,the Ford was also full pressure,both the flattie and overhead valve six and the block cracking flattie V-8's.
Chevy outsold all the others cause the Chevy must have been a better value for the money at the time.
