8.9:1 ey

, you have run it before right? did your speedy get hot? From Shauns gearing i reckon around 15-16:1 seems about right. 18.92:1 would be alot safer, but make sure you dont go too far and undergear it, then the motor might start getting toasty. Drag adjusted of 82mph, thats insane specially with a 1515

Keep us posted with how your changes go, have you got the RCM hybrid diffs on your truck? Im assuming you have the buggy diffs in now?