If that's the rear end I'm thinking of, it was very very hard to find it in a 4.11 and it wasn't it a 4.10? So maybe I"m on a different rear end. It was way more common in a 4.57. If it's the one I'm thinking of, it's the 3/4 ton GM Corporate rear end used in the 60's and early 70's. Man, I looked and looked and looked for a 4.10 forever back in the 80's. We had 3 3/4 ton trucks between my dad, bro and I. All had 4.57. I finally 1 day hit pay dirt at a Pull A Part type place. I had opened up probably 30 of them things hoping to find a 4.10. Never did, til one day a 70-72 Ambolance was in the Pull A Part. BINGO !!! 4.10 ratio. Dropped that bish out and took it home. Cost me a whole whoppin' $50 and I was happy to pay it. BTW, 4.10 and 4.57 were the only ratios offered in that axle in OE. I'd imagine you can get what you want aftermarket.