There were no six cylinder Buicks from 1931 until the early 1960s. Straight eights only through 1952, then 1953 introduced the V8 in the Super, the Roadmaster and the Skylark. The '53 Special was the last of the straight eights.
Thanks! I wish I knew what happened to my bulletins and I also had a parts interchange book that disappeared. :( At least I still have the 1950 shop manual that belonged to my dad and the 1952 shop manual that was a gift from a friend.
The factory put out a bulletin on this problem back in the early '50s. Their fix was to dismount the tires from the wheels, weld a small piece of rod to the wheel and slot the corresponding wheel cover tab. Somewhere over the years, coupled with various moves, I have lost my bulletins that I found.