Go to 5speeds.com. The world class T5's were introduced in the late 80's. Also, the 82-92 T5's bolt right up to the Chevrolet/GMC bellhousings. In some cases you have to have a spacer betwen the trans and bellhousing, or cut some material off the end of the pilot shaft, and also the throwout bearing sleeve. This depends a lot on the clutch disc you use. On my first conversion I used an S10 9" disc and the center hub of the disc was thick enough to require cutting the throwout shaft. I have since changed over to two Camaro T5's one WC and one NWC. If you can find a pre 87 S10 tailshaft housing, you can build a Camaro WC with the shifter in nearly the same place as the original 4 speed.
