I remember several years ago, a company that sells ring and pinion upgrades for AD trucks stating that the swap was more favorable with trucks that had been upgraded with a 235 and the extra horsepower. Trucks that retained the 216, and especially those with the 3 speed, might have less favorable results. Trucks with the 216 and 4 speed at least had some low speed pulling power in a pinch.
Also think. Would you really want to drive 60-70 in one of these trucks in stock form? I worked as a body man in a restoration shop for years and once had the opportunity to go with the mechanic on a test ride in an AD truck that we had installed a 350 and automatic and an open late rear end in. Straight front axle and drum brakes were intact and it was a white knuckle drive . Wide tires and mag wheels caused bump steer on bumps and railroad tracks. If you want it to drive and handle like a new truck, buy a new truck. As a retired restoration guy that has witnessed some of the prices charged and some of the divorces that resulted, it is often cheaper to buy a new one.
