There are a couple of different types of five-speed manual transmissions available for classic Mustangs. This is the Tremec TKO 3550 five-speed with hydraulic clutch. It will take quite a pounding from a high-performance small-block. However, if you're running a sedate little 289 or 302, a Tremec T5 is a perfect fit. Don't forget that small-block Fords prior to '82 have 28-ounce offset balance flywheels. From '82-up, 50-ounce offset balance. This is crucial to smooth operation.