Dongray,
I specialize in T5 transmissions. I like to help folks figure out how to get them working in older Chevy trucks.
Your dilemma is a good one. I have a few bits of advice. The advice given so far is good stuff.
1. Figure out what rear axle gear you have. (The 2nd generation Camaro rear if you have settled on that).
2. Use
THIS RPM CALCULATOR to figure out what RPMs will be for 65 MPH. You'll need to know the rear tire diameter. Use 0.73 for the transmission ratio because that's a common T5 OD gear.
3. If your Camaro rear axle gear is higher than 3.42 (lower numerically) then a 0.73 OD gear will not work very well. You'd probably be happier with the SM420.
Multiple factors need to be considered before deciding to use a T5. A T5 from 1992 and earlier will bolt right up to a bell housing with a Muncie bolt pattern. The 1993 and earlier S10 T5 has a Muncie bolt pattern as does the 1992 and earlier Camaro T5. Later model T5 trannys have a FORD case pattern.
As you are aware, the S10 T5 with a cable speedometer connection is very hard to find these days. I used to find one or two a year but not any more. So if you want a working cable driven speedometer on your dash, the SM420 is the easier answer.
First things first . . . . what is the rear axle gear in the Camaro rear?
