HD used a Delco-Remy starter on the first e start Pans and maybe into the really early shovelhead years. Then they switched over to Prestolite. The Prestolite motor is also used on Sportsters through about '78, with a different drive housing. In about '73 or so, HD began using Hitachi starter motors on the FX series, but continued with the Prestolite on the FL series. You can use either motor on either bike, as long as you use the drive housing that goes with it.