Huh??? Assuming you have the .68 OD T5, final for 3.55 will only be 2.41... I run 3.73 in the T-Bird with AOD & lockup converter with same O/D ratio, final is 2.54...
Yep, I have a 3.00:1 with a World Class T5. I shift into 5th gear around 40-45 mph and stay in 5th going up hills as long as I'm doing 40+. Gotta love the bottom end torque that you get with a 6 cylinder. At 1900 rpm I'm rolling at 80 mph and get around 28 -30 mpg
For fuel economy, if you don't have Overdrive, I'd suggest the 3.00:1. For Performance, I'd suggest 3.40 or 3.55. For racing....well....more than that.