According to "OldGMCTrucks" Truck Model Identification ALL "35x" came with a 248 CID engine from 1947 through 1954. No other options are listed.

The still does not mean someone along the way did not replace the engine with something larger.

http://www.oldgmctrucks.com/page0191.html

[x denotes numbers 1 thru 5]

Good Luck and Happy Motoring wink

Dance like no one is watching,
Sing like no one is listening,
Love like you've never been hurt.

1948 GMC FC101 1/2t Pickup w/270 and SM420
1948 GMC FC253 1t Factory 80"x9' Flatbed Dually
1948 Chevy COE 2 Ton 8'x15' Flatbed
1950 GMC 354-24 2 Ton 8'X12' Flatbed w/Dump Hoist
1953 GMC 454-30 3 Ton 8'x14' Flatbed w/Dump Hoist
1953 GMC 454-30 3 Ton Cab and Chassis
1942 Clarkator 6 MILL-44 Heavy Aircraft Tug
1942 Ford (9N) Moto Tug with 1/2 yard Loader
1947 Oliver OC3 HG-42 Tract-Crawler Bull Dozier w/6' Blade