I have an 88 5.0/HO with AOD trans and 8" rear with 2.78 Gears. (not original rear). The trans will not stay in OD unless I'm doing about 70mph, otherwise it starts hunting for the right gear based on rpm. What would be a good all around gear ratio, non-posi? 3:23, 3:55 ??? Thanks for the help.
3.55 or 4.10 depending on how much freeway commuting you do
I like the 3.55's for a good al around gear.The 3.73 or 4.10 for more performance.I do a lot of highway driving,so 3.55's are it.
4.10's for me. I have done highway cruising with them and they aren't bad.
By the way chances are you have an 8.8" with a 2.73 gear (thats what a lot of mustangs had).
Theres a lot of different opinions on how 'okay' different gears are on the highway. Some people will say 4.10' or even 4.30's are okay on the highway, while some say they arent. Youll probably only lose a couple mpg between 3.55 and 4.10. One things for sure, it would be better around town.
Obviously if youre trying to keep cruising rpms down then a taller gear would be better, 3.08-3.55. But if you really want an harder punch off the line 3.73-4.10+ would be the right choice.
I run 3.73 gears with mine. Nice and they are fine on the highway in OD.
X2 or X3, whatever...
With automatic and a performance cam, I wouldn't run anything less than 3.73s... The 3.55 are good with a stock HO cam...
Even 4.10s are no concern with the OD trannys... Final ratio in OD is 2.74... I have a Aerostar with 3.0 and 4.10s FACTORY, and of course the Lightning has 4.10s...
Motive and Strange make a 3.90:1 that's a nice compromise between 3.73s and 4.10s. That's what I would go with.