1 7/8" small block B/E body TTI...if I had to do it over, I would have designed my own not that theres anything wrong with the TTI's although I did have to modify my Milodon Pro Touring oil pan slightly for clearance issues. Heres a picture after I had them Ceramic Coated...I also added Flomaster ball and socket collectors for a little added body to collector clearance since I raised the motor in the chassis some.