Well, the mounting area for spacer kits is a direct-fit no matter whether it's a 70mm or 75mm TB. The plastic TB mounts are the same. The bolts and gaskets for 70mm/75mm are the same size since both TB are the same size. So they'll mount correctly from the TB to uim plenum elbow perfectly. The plastic gasket that came with this TB is roughly 3-1/2 inches length/height for either mm TB.