'59 235 with the factory 4-speed and a limited slip diff that, if I counted the revolutions correctly, is a 3.90. The brand new tires that came with the truck are 235/75/15's.
How much benefit will I get from changing the diif to a 3.58? That's all the guy at Arizona Differential says he can do with that diff and he charges $800 for the work. My goal is increased cruising speed (70 mph?) so we can use it for our annual cross-country vacation as well as occasional freeway driving locally.
I don't understand diffs, suspect they're magic of some dark sort, so can't tell if the cost/benefit ratio makes sense.
Thanks.
