JonBeast

You should be able to find all your answers here:

https://mustangforums.com/m_600073/tm.htm

mustangdad

Rear gear ratio selection depends on what your goal is with the car as a previous poster said. If your a weekend racer and absolutely want that better out of the hole acceleration than stock 273's suck. If you very seldom do any highway driving than 373 or even 410 would be the way to go to win races over a similar stock car with everything else being relatively the same in both cars. But everything has a trade off and gears are no exception. I just got out of my car and a few minutes ago I took 2nd gear up to about 4200 rpms then upshifted to 3rd and continued accelerating to about 3800 rpms and I was doing about 77 mph. Now with 373 or 410 I would have seen higher rpms and for my particular preference I dont like that. Those speed/gear/rpm calculator tables don't take hills into account or any other factors of the real world. So when you see only 200 rpm or so over stock,you think hey I can deal with that I'm going for that bigger gearset. But if you have the chance to drive a Mustang with a bigger gearset than yours I would really recommend it. I hardly ever shift above 3500 rpm's in normal driving except maybe for a quick highway merge. My car has high mileage so I don't want or need to rev the crap out of it or have it or cause more wear on my synchros/clutch from shifting alot. I love being able to light a cigar while I am in 3rd gear and knowing that I am safe from having to reach for the shifter from 22 mph to about 70 mph if need be. 3rd gear is supposed to your all around most usable gear. With a gear swap of too high a numeric youll be using 4th to attain pretty much the same result as the stocker does in 3rd. 5th on the highway is your overdrive gear. Its also pretty dead for a roll on acceleration unless your in the cars powerband which with stock 273 gears would mean your going like 105 mph or so. With 373's 5th gear just rolls right out,no downshifting to 4th needed if your going like 70-75 mph which is more realistic than 105mph. So that was nice about the 373's to me. And yes I definetly burned more fuel,I could tell by the gauge I didn't figure it out with a calculator but I just know.

wwmost

lm1's you dont have to break in or nothin cuz there is nothin in there.