well the 67 to 72 GM 3/4 ton automatic is the only easy 2 hour pig/pumpkin swap gets you from 4.57 to 4.10

There are kits avable to change the ring & pinion gears to get you in to the 3.s

there is a( rear end swap and what to use)on the chevytrucks.org site full of info.

thanks to all for the help and good luck to the all who diecide to change gear ratios. thanks Bill

Bill 1951 3/4 ton 5 window pick up
1955 GMC 1/2 ton longbed automatic