Tremec T-56 magnum question

[toomnymods]

I'm about to buy a used Tremec T-56 magnum from a guy that has approximatly 10k n/a miles on it. He bought the car used with the T-56 magnum already installed and he can't get ahold of the prior owner. How can I find out what gearset he has installed? will the part number give any info? does it have the gearing of each gear stamped onto the case somewhere?
Trying to figure out if my 3.73 gears will be enough when i twin turbo it in a few weeks.
Thanks

 

[blackbeast12]

I own a tremec and the casing serial # will not tell you what gears are in it as gears are often added and removed after the fact. The best way to figure it out is to install it with 3:73 gears and calculate the rpms speed tire size to get the gear ratio. If you have the 2.66 version then you would still be ok with 3:73's and a twin turbo. I have a Paxton and the 2.77 version of the Tremec with ford racing 4:10's. So with 4:10's you would be good to. If you were naturally aspirated with the 2.66 you would need at least 4:56's for proper accelleration. There's alot of flexibility with the twin turbo because they make so much power!

 

[4VFTW]

cant you put it in gear and turn the input shaft 1 turn and watch the output flange or vice versa?

 

[blackbeast12]

This app should help you narrow it down:

http://xse.com/leres/bin/gearratio?...4.82&revs=747&section=285&profile=35&wheel=19