Russ, I was told...don't know if it is true or not...that the older version are the ones on the drivers side of your truck with the smaller hand holds and the smooth cones from the hand holds to where the edge of the hubcap meets the rim...and the newer version are the ones on your passenger side with the stepped cones and larger hand holds.
Both versions were made by Kelsey Hayes.
I have the stepped cone version on my '57 3600.
Once again hearsay, but I've been told the switch from old to new happened when Chevy changed from AD models to TF models midway through 1955.
Matt
