Dear All,
I have a Ford Mustang, 1989, auto tranny that I recently pulled then put back in when I rebuilt the motor. All that was done to the tranny was new filterand fluid. Since then the tranny will not shift out of 2nd gear? Tachometer is also gone haywire and shows higher rpm than actual. Need some possible ideas as to what is wrong.
Thanks,
Caseih1460

I'm not certain but it could be many things. I'd check:

Valve Body bolts loose/too tight
Sticking valves dirty/ports blocked
Missasembled oil filter
Misadjusted linkage to mnual valve
Mainline pressure
Governor valve
Valve body ckeck balls

Hope this help narrow things down