I have a ‘55 370 conventional, 18,000 gross, rear axle and front hubs and steering gear, but 5/10 lug wheels. Added 5/10 lug front disc brake hubs/spindles from GM P-3500 rear D-80 w/ disc brake, 5/10 lug axle to match front.
Tubeless wheels exist for your 6 lug bolt pattern.
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.