The Posi unit
This is the Auburn Pro posi unit. I kept the original 3.73 gears, but had every bearing, race & seal replaced. I do all of my own motor work, but I opted to have a local guy do the setup on the Auburn unit. He painted the inside with the oil slick paint and did an excellent job on the setup. The rear end has since withstood the modified 305, as well as 2 other much healthier smallblocks.
Here it's almost done being installed. Some new Monroe shocks help eliminate any wheel hop. Not that the 305 would've had a lot of trouble with that. The rear brakes were completely rebuilt while the rear was out. I also put a drain plug in the bottom of the housing, so fluid changes can be done without removing the "pumpkin" cover.