You seem to have the standard setup for a 3/4 Ton. The rearend is known as an HO52. You won't find a bolt in OD transmission as any of them would require changes. The change in the rearend gearset to 4.10 is a bolt in.

1951 GMC 1 Ton Flatbed -- It is finally on the road and what a great time I have driving it!
1951 1 Ton Completed

My Chevy Master 4 Door is on the Road!