Looking at three boosters that I own. One seems to have a longer rod with a hex shape around the thru bolt end of the rod. The other is completely round at the thru bolt rod end and seems to be about an inch or two shorter. My T/A I beleive is using the shorter style and has an offset (bellcrank) under the dash which offsets the pivot point. I was wondering what the longer rod application may be for and what the different applications are all about considering they are all for power disc brake cars?