hydraulic and mechanical

Caveman, hyd. and mechanicals take different pushrods. The lifters are different heights (lenghts). Adjustable rockers work on both...If you have adjustable rockers, all you will need is the cam and lifters with the matching pushrods. Mechanicals (flat tappet) make on the average, 3 to 5 % more power than hyd. do..ALL else being equal. However...the newer high lift hyd. cams, (XE/HL) as an example, are getting closer to solids. Good luck, Terry.