but if you’ve got the peanut rear end, you might consider to swap out to a 9”.
I bought a 9” rear end from a scrap yard down there for $350.
Barnabas wrote:That 4.11 rear axle is common to the Heavy-Duty Econolines. It's great when hauling heavy loads around town, but not so great on the highway. As mentioned a 3.5 would be better.
Larger diameter tires would help as well. You probably have 14" rims, but 15" rims will fit. And 14" tires are harder to find now. My 1964 Heavy-Duty Econoline came with the 4:11 rear, 170 engine, and 13" tires. That was not fun on the highway!
If you change the rear axle or tire size, you may want to change the speedometer gear in the transmission to make the speedometer read correctly.