Hurst built these years ago to help put different motors in (mostly) early frames. Is there information anywhere that shows the various dimensions and differences that would allow a person to help identify one from the other? I came across one some time ago and have no clue what motor it might have been made for. The one I have is near 20" from cushion mounting slot to mounting slot. There are two pair of block mounting holes that measure approx 9" apart and 8" apart. .