[Jack21]

Went through the same decision process.

The T5 is smoother, but is limited in abuse tolerance. The Tremec will take more abuse.

I went the T-5 route, but along the way I learned the only T5 to use on a 351 Cobra is the T5Z (2.95 low) new, from SVO. These were not fitted on any production Mustangs, so you won't find them on donors. I bought a blueprinted T5Z from Liberty Transmissions, and put a Hurst shifter in it.

The engine I'm using is a tweaked 351W, street tires, and is a street only car. I typically baby a car anyway, so the trans should last awhile.