302's came in big

GMC trucks after '53 or so, some military trucks, some comm'l special trucks, saw one in a milk truck. Have been put in smaller trucks. Also Korean War 10 wheelers with a hydromatic trans.

Some military or big truck ones have a 14" clutch, big bellhousing that is awkward to use, so, if you come across a smaller one(270 for example) get the flywheel and bellhousing for a 12" clutch. A GM HEI distributor for a 230-250-292 GM(Chevy) and even fire V6 will work in 270-302 engines,
.
I guess you know the SN starts with the displacement, I.e. 302xxxx, stamped # on casting behind starter.

Ed

'37 GMC T-18 w/ DD 4-53T, RTO-610, 6231 aux., '95 GMC running gear, full disc brakes, power steering, 22.5 wheels and tires.
'47 GMC 1 ton w/ 302, NP-540, 4wd, full width Blazer front axle.
'54 GMC 630 w/ 503 gasser, 5 speed, ex fire truck, shortened WB 4', install 8' bed.
'55 GMC 370 w/270, 420 4 speed, grain, dump bed truck from ND. Works OK.