I am hoping to find a copy of the repair manual for my 1961 Kiekhaefer Mercury, Merc 500, 50 hp, 4 cyl/2 stroke that is on the 1961 Texas Maid Fiesta. Also is there a major difference between the '61 and '65 Mercury 50hp outboards? I see ther are repair manuals that go back to 1965 on here but...