This is the Tilton 61-601 hydraulic throw out unit. See the inside of the bore with the threads? That is so you can use the base Tilton sells separately that screws in. The thread allows you to adjust the bearing height to the proper distance. Well, the Tilton unit, even without the base, is too long to use. So, we had to do a little modifying. The first thing I did was take a piece of aluminum and make a ring that we could press into the back of the unit. The ring is to reduce the size of the bore so it will fit over the input shaft collar of the Tremec tranny. Of course, the unit is too small to fit over the collar, so we had to lathe 0.033" off the collar shaft. Then I pressed the little aluminum ring (0.001 interference fit) into the back of the hydraulic unit. Then everything lined up perfectly...but it was still too long.
