The boat is a 17'4" tri hull,and the trailer has 2 12" rollers, 1 in back and 1 middle and 2 6" rollers forward and 1 v stop along with 2 bunk rails.<br /> I need to replace them all and I have spent along time restoring this 71' pipstone mariner it has a mercruiser 140.I/O tri hull runabout.<br...