8.75 rear in 71 swinger slant six car?

Years ago I bought a 71 Valiant 4 door from the original owner who ordered it brand new.. he was going to do some towing with it so ordered the HD axle - 8.75 with 3.23 gears and a Sure Grip. For mileage he said he ordered it with a slant. Whatever!

Edit: it had Kelsey Hayes discs as well