I just replaced the stock two speed with a disc brake D-80 in mine, bolted right up. Axle tube on D is .25” smaller, made curved spacers, new U bolts, removed a few leaves, adjusted pinion shim. Used D axle shock mounts. The axle is the less desirable one to some, about 7’ wide outside of duals. Easy job. Installed one of my of my spare 5500 Brownies to give more gears.
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.
