Looks like a '54 first series(two piece windshield). Timken two speed rear axles had ratios of slow and slower, if fitted. Low not of much use. 4 speed should be SM-420, good trans. Shift lever on diff. will identify if single or two speed. Engine should be 235 or 261, unless downsized for OZ?

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.