Did the old fashioned research and found a few things but I need some clarification on a few points. Here's the issue: installed a new McCleod clutch kit and when testing found that it made a rumblimg sound when depressing clutch pedal and would not even come close to working, could not get in any gear with out grinding gears bad. Have adjustment rod adusted all the way out as far as possible and still no go. Read where Joel says there are 2 sizes of T/O bearings. Joel, do you have numbers for these bearings and could this be the problem? The old clutch had to be adjusted all the way out to the end of the rod also to get the freeplay in pedal and the T/O bearings new and old are the same. Also read that the fork and pivot ball should be replaced too. I did not do this. Another possible cause? Don't have a clue about the rumble, maybe because of being new??? My son-in-law did this part of the job for me and he has done many clutches, says he installed the T/O correctly  BTW the application for for this clutch #MCL-75121 from Summit says it fits Corvette from 1969 to 1980. HELP! I need to get this done for Friday to to Ocean City, MD for cruise on the boardwalk!!!