I never kept up on the 273's . most of the cars I bought were 340's . By the 273 cars I did buy. I was always under the impression they solid lifter motors this one is hyd. . You learn something new on these cars everyday. I once had a 67 Satellite it was a 318 with solids. That I thought was done by someone. Since then I have been finding those rockers on several 318's.