Hoyt,
Maybe I am reading it incorrectly. However, it looks to me that the page you linked confirmed what I posted from an earlier page: some Utility Body 235/261 had the 5/8" pulley in 53-55. All other 54/55 6 cylinders appear to have used a 3/8" pulley.
The belt lengths are helpful but, for some reason, I recently found that I had to go back for different size belts when using a 1954 3/8" 235 water pump and 6v generator on a 1960 261 with 3/8" pulley on the harmonic balancer. This might have been due to the different locations that the generator adjustment-arm attaches to the engine?
Tim
