Hy electors, distributors are physically interchangeable between 216, 235, and 261, there are different part numbers for the different engines, those different numbers represent the parts (vacuum advance, advance weights and springs) that the engineers felt would work well with that particular engines specifications. In 1955 we had two different truck designs, the first or "A" series which looks like a 54, and the second or "B" series which looks like a 55 and newer. Your distributor is listed as applicable to all 235 powered trucks in the 55 second or "B" series, hope that helps.
