I got and 81ford f-100 straight six 4 speed 2.47, open diff, 9" ring gear...
im bout to go get me another rearend... i want one that will wake my staight six up.....WHAT SHOULD I GET????? what to expect with the new rearend??

THANX FOR THE HELP

 

Without an overdrive 5 Spd. trans. I wouldn't go much over 3.50:1. Especially if you do any highway driving.

 

I agree about the 3.50 gear unless your running oversized tires, then might want to go a little higher. If your axles are ok just buy the ring & pinion or a used third member. Cheaper that way esp if you buy less than a 3.50 gear ratio third member.