[1969 GMC]

I believe 3.54 is the lowest gear ratio available for D60's.

There was a D61 found in some Dodges and Fords, that could go down to 3.07, but its an oddball axle.

Front and rear D60 gearsets interchange (with the exception of Ford "hi-pinion" and the above mentioned D61 gears). The only difference is some of the older gearsets might have a coarse splined pinion gear, so just grab the yoke if you do get used.