The unmounted dually is a 5 on 8, which is not stock. However, that bolt pattern is available as 22.5 tubeless, so check carefully. Definitely a 2 speed, ratios are usually slow and slower, not very useful. Numbers stamped just behind distr. will tell displacement.

There are lots of 302's around, military just do not have side engine mounts, do not pass one up.

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.