I have never seen a 6 lug 3/4 ton... if you have 6 bolt pattern it is more than likely a corporate 12 Bolt with 8-7/8" Ring Gear and 30 Spline Pinion. 3/4 ton would have 8 bolts and prob be a corp 14 bolt.
1/2 ton has fewer leaf springs in the back... 3/4 and 1 ton are thick stacked. ( my...