I have 68 C20 that had 4.56 gears and leaf springs. I replaced it with a 73 C20 or 30 that had a big block and auto in it. The axle was a rear loader with 3.73 gears and a sway bar.
The 73 axle was bigger, larger brakes, and bolted right in. It was also wider, but I didn't have problems with wheel clearance. The only problem I had was one shock was angled forward and the other back. To make the one angled back work I used a shock bolt from the front in slotted hole that was already in the frame with a washer. I then welded the washer to the frame. It was a tight fit, but haven't had any problems in three years. The 16 inch wheels I'm running are from a 92 chevy truck. Hope that helps.
Larry
