RPM With 3.73 gears
 

can anybody with a 98 gt that has the t45 tranny and 3.73 gears please telll me your rpms at 50 mph when i bought my car the guy said he put 3.73`s in the rear .when i`m doing 50 mph my tach reads 1700 rpm and at 70 i`m only at 2000 rpm this don`t sound right and it feels like i still have the 2.73 cruising i don`t realy want to take the diff cover off and count the gears but i might have to if you people can not help:confused:

Well.... If you went from 2.73 to 3.73 then that should be an easy test. Jack your car up in the rear, put the tranny in neutral and spin your drive shaft over. Count the number of turns it takes to rotate your tires one full turn, and that's your Ratio... since you know what you had, and what you went to.. your not having to be very precise as you would trying to figure out a 3.08 > 3.73, or 3.27>3.73... You will see one whole turn extra on your drive shaft if you do infact have 3.73, other wise you will only see about 2 and 3/4 turns (2.73).. That should help... If I am wrong about this, someone let me know, this is how I have always heard to do it.

At 50 mph, my tack is at 2300 RPM in 4th gear.