On older GM vans you could custom order you running gear, un like today.
also on the GM 12 bolts the gear raitos can be swapped out.This involves not only the gear set them selves but the carriers also
the 3:08 rear gear set I am running in my Early came out of a 79 pick up.
I went from a factory 4:10 to a newer 3:08 doing this swap.
The 12 bolt housing its self from 69 to 79 where the same.......

........Wookee

Good to know I can swap ring gear and gears inside the 12 bolt housing. For now the 3.07 gear is good enough to use. The important thing is I now have 5 x 5 bolt pattern on my van - no more 4.75 by 5 size!

I also found out the ratio gears were stamped on September 1974 ... so it does match the age of the van where I got the axle, the dates looks to match all round by parts. The van obviously retain much of its original parts on it.

A shame that the van is so rusty - it was an old vanner's van. Someone swooped the fender emblems and what looks like corvette waving flags above the emblems. I can see the shadow lines on fenders.

I like the 3:07 I am currently running in my Early.
Exalent light to light performance good hi way cruising speeds and MPG arew not too bad ether........

.........Wookee