Mine runs a little faster than that at 65, closer to 1900-1950. Running a 3:55 rear. I have a T5 from Mike Forte purchased in 2005. I have no clue what the ratio is in it. From what I've read it's most likely 0.68:1.
I found this article you might find helpful.... http://www.carcraft.com/howto/116_0609_t5_transmission/index.html

 

This should help you with your figuring; http://www.1bad69.com/calc.htm
You definitely need to take your motor setup into account when planning your gearing. If you have a low rpm high torque motor, by all means go with the .63, but if you are running a hot cam and intake setup the motor will not be happy at just 1800. Plus a .63 means that you have a huge rpm drop between fourth and fifth. That is great if you really want your fifth gear primarily just as a highway overdrive.
My future plans are somewhat the opposite and include changing my .63 fifth to a .79 or so. This should make the tranny more of a true five speed and much more usable for the secondary roads that I prefer to drive. The 3.27 rear end allows for a nice longer first gear, and as you will see when you play around with the link, a reasonable 2185 rpm at 65 when I switch to a shorter fifth. The cam should then be more efficiently in it's rpm range.

 

Thank guys, keep them comin!

My power band is 1800-5500. But I need to take a closer look at difference from 4th to 5th. I guess I'm knee-jerk reacting alittle since my daily drive is 60 miles each way in a small car where 5th gear has the engine buzzing at 3250. After an hour of that, I'm buzzing too.

I need to consider how much time I'll spend on secondarys too. Its gotta be more than highways. I don't live in the real West.

 

5th gear

Hi Daddy-O,
I sell the new T-5 world class and it comes with a .63 5th gear. I can install a .73 5th gear if desired for extra $$$s if you want....

 

hey mike

Mike,
That new t-5 is that the Z? Can that be had with the .8 5th?

 

What rear gear you are running has a big effect on what OD ratio you want. So what is it?