40 Chevy,

So your rear is 5 lug also, that would work if they are on 7.25” circle, might have to find 19.5” wheels, slightly smaller than 20’s, but might look OK on your year truck.

The 3500 series axle has to have the tie rod behind the axle. This may be too much effort and $ for your truck, unless you are going to drive with loads extensively.

If you get that rear axle, unless you find 10 lug wheels, if you can find one 10 lug wheel, only need the bolt pattern in the center, you could lay it over your existing wheel, making sure the bolts line up perfectly or make a dummy hub to center the wheels, and drill new holes in your 5 lug wheels using a drill bushing, you could make or have made since the wheels are hubcentric.

Good luck,

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.