Identifying gear set

[66fstbk88]

How can I tell what kind of gears I have?.. I'm in tha process of getting ready for my tko swap and can't remember if I have 3.25 or 3.50 Gears. Would either gear set make a diffrence on what type of tko fits better for my application?

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[groho]

jack you car up, both tires, turn the tire 360 degrees and count the revolutions of the drive shaft. I'm not a TKO guy, but I believe this forum mentions there's two ratios of gearing for a TKO. The dif between 3:25 and 3:50 rear gears would be roughly 200-300 RPM at the most. This wouldn't matter on the street.

[1971mach1]

I think it may make a big difference in wheather 1st gear is useable or if it winds up too quick to be useful on the street (like a granny gear) or the opposite, you have no power because it's too tall.
It also depends on tire diameter too (tire not wheel). Larger tires make the effective ratio taller.
I went with a TKO-500 (3.27 first gear) because my rear gear was 3.00 and tire is 25.5".
If you have 3.25 gears w/same tires, I think you'll still be ok with the TKO-500. But 3.55 I think you'll rev up too quick for 1st gear and would be better off with the TKO-600 (1st gear 2.87). But if you have larger tires, maybe the TKO-500 would still be ok w/ 3.55. As you can see, there's a big diff between 1st gear ratios on the TKOs, so choose carefully and you won't have to change rear gears too. Maybe ask Tremec or the trans dealer too, if you're not sure.
5th gear there's a choice too, but it's easier to calculate (like at 70mph = 2k rpm).
There's a nice gear calculator at ringpinion.com