to tell if your clutch is going put it in 6th at a lower rpm and floor it. if your rpms go up but you dont go anywhere your clutch is going
if you do go then perhaps you need to change the tranny fluid.
for fluid our team guru suggested valvoline 80/90 synthetic (kragen out here sells it) you will need 3 qts. I like valvoline anyways (all my fluids are from them) and I was not disappointed when I switched to it from factory stuff.