Factory 8 3/4 with 3:31 Gears?

Found an 8 3/4 741 case for sale. Seller says it's from a 64 B-body and that it has 3:31 gears. Just wondering if that ratio was ever offered. I haven't gone to look at it yet to verify the ratio. I've seen all the usual ratios, 2:94, 3:23, 3:55 and 3:91, but this is the first time I've heard of a 3:31. Is it possible this was offered or perhaps aftermarket?

Would that be 43/13 r&P? never heard of it in 8.75

That might be a gear set from possibly a late 50s early 60s car or truck. I remember my brother using one in his 64 Fury that he bought new,but it came with a 3:23.

The original rear in my 59 Coronet was an 8 3/4 with 3.31 gears.

My '57 New Yorker had 3.31's......they were used in the '57-'61 version of the 8 3/4 axle. I believe the carrier number started with "18xxxxx".

The 3.31 was the 3.23 of the fifties.

Not offered in '64 in the 8 3/4". Check the date on the ring gear.