Hy Grigg and guys, the first mention of the pattern ten stud on 8 3/4" circle, is 1960 C50 and L50 they are referred to as "Kelsey type wheels [standard]" they continue to the S50 series, and up to the C,L,T, and S 60 series, but are not available for the heavy duty option in those series, on the heavy duty side your only options were "Budd mounting type [option 172]", or "Cast spoke wheels [standard]", those are what we commonly call "Daytons". the 70 series and above used only the "Cast spoke wheel rims [standard]", or "Budd mounting type [option 172], hope that helps.