The 1955 front variations got more complicated with the additions of Robinson and Williams. The Williams was pretty easy to find, the Robinson less so. Getting all 4 Elliots was challenging too.
https://www.tcdb.com/Errors.cfm/sid/36/1955-Topps
I did the alternative backs for 1959 and 1960. The red v black for 52 are not hard but the gray backs 131 to 180 are hard and expensive. Same for 1-50 in 1954. They are not hard in 1956 but expensive because of so many stars.
Vrechek article on 55 variants
https://r.search.yahoo.com/_ylt=A2KI...tYaTNrHn_SC9U-