I used a straight axle P3500 HD for my '37 GMC. Front axle and rear axle with disc brakes, hydroboost, Saginaw power steering. I was able to space out the front fenders to fit the axle width, which you cannot do.

Grigg wrote several good articles about installing modern disc brake spindles on an AD axle.

Saginaw steering boxes come in cross and fore and aft movement of the Pittman arm, same box, just different mounting, Pittman arms. GM 4wd and 2wd have the two.

D 70 and 80 rear axles come on these vehicles, so lots of options there.

The truck had 19.5 wheels and tires(10 on 7.25" bolt pattern) which, while the are great tires, they look undernourished on an AD truck. Early 22.5" wheels with this bolt pattern are great but rare. No-one makes modern 22.5 wheels with his bolt pattern.

Hydroboost and power steering work great.

Good luck.


Last edited by EdPruss; 05/24/2015 10:32 PM.
'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.