Hi all,hope everyones doing good. Heres a fun question concerning rear axle ratio.Heres the drivetrain so far. A ford 200cid straight six with a factory 3 spd toploader transmission. Ok, so,, I got a good deal on a ford 9" which turns out to be from a 75 torino.I know this is not an ideal lineup ,but am working with what I have. I would like to find a rear differential ratio that would let me drive on the highway and keep the rpms down. What ratios are available for 9" that would even do that? The tag was missing from the differential so Im guessing its stock.