Quote Originally Posted by hammerhead View Post
My 79 is factory 302/with 345 my 90 was a 302 with factory 355 - I would think with the addition of the 5spd and taller tire 16" the rear gearing was bumped to 355 - four cylinder rear end may be 273 as it was a completely different transmission in 79 - 81 anyway but I think it was also 345 to make it feel as this it had power lol
Your 90 would not have been 3.55 from the factory, all 87-93 Mustang 5.0 had 2.73 or 3.08 as a no-cost option. It did not change with the 16" in 1991 since the overall tire diameter was the same. If you get the axle code from the door VIN and info decal you can verify what it was originally.


cheers
Ed