It sounds like the starter bendix is not meshing with the flywheel. You need to align the starter so that the two mesh. Shims are sometimes required and should have come in the box with the new starter. Check to see if they were there and if not ask the FLAPS about them.

"If it ain't Steel it ain't Real"
"Earth the insane aslyum for the rest of the Universe"
41 1/2-ton, a work in progress
68 Shortbed stepside 327/325hp/700R4