I may be wrong, but I think the 53 and the 551st both had there springs run under the axle. 552nd and later had the spring on top of the axle.
Also check where the locating pin on your spring is. I believe the 1953 locator pin is not in the center of the perch but about an inch ahead. The 1955 1st series pin is in the center. There are kits that change the locator pin to the correct location.
Bill Schickling
