I have a 1994 Chevy blazer full size 4x4 5.7 liter v8

I have a 1994 Chevy blazer full size
4x4 5.7 liter v8 transmission was
working fine before we replaced the
front main seal hooked it all back up
added fluid it runs through all the
almost like it wantS to go into gear
but does not when I put it back into
park it makes a little grinding noise
also. I'm able to drive it in four wheel
low And high any idea what could be
the issue?