89RsPower!

I have a 700r4 sitting around that shifts normally through first gear and into second and will not shift past second gear. It doesn't upshift into 3rd or 4th, it just stays in 2nd. It doesn't slip at all in first or second, it just will not shift past second gear.. I'm planning on rebuilding it to replace the slipping tranny in my Iroc, just wondering if there is anything specific that would prevent it from shifting past 2nd... I'm use to these tranny's shifting through first, second, and then start slipping in 3rd and 4th when they're on their way out... what specifically would prevent it from even attempting to upshift?