1997 Chevy Truck what do I need to replace

Transmission problem
1997 Chevy Truck V8 Four Wheel Drive Automatic

i have no reverse at all and to get into second gear I have to rev up then take foot off gas and it will shift o prob no second gear and max speed is prob like 70 thats all I could do when I nursed it home do ineed to get whole new or what specifically do I need to fix