GMC had full pressure oiling starting in 1938, w/ the 228 engine. The 302 looks the same and is the same in external dimensions as a 228, about 100 lbs. heavier than the 194-292 Chevy engine. GMC and 194-292 are about the same length, about 2' longer than 235-261.
GMC Ser. No. starts w/ the displacement, i. e. 270xxxxx. 302xxxxxx, so look for a 302, parts are same price as 228, and you will have plenty of power. 302's come w/ 14' flywheels(too big) and 11" ones, so if you get one w/ the big flywheel, you will have to get the appropriate flywheel and bellhousing w/ the pedal mounting holes in it-same as Chevy bellhousing.
Where are you located? 302's only came in big trucks, however, one may have been swapped in a smaller truck. 270's are very common and a good alternative if you can't find a 302.
Ed Pruss
Longmont, CO
