Ted... my car is 3350#, runs high 9's and using a trans brake. I can get about a year out of a set of street gears (Dana 60) before the pinion teeth start to fail. If I foot brake, I can nearly tripple that. For me, a pro set of gears are the way to go. When the rearend wine get noticeably louder, it's telling me to change them out. For me, its easier and quicker to change out gears before they fail completely then to tear down the trans and inspect the sprag. It's your choice, just offering up some personal experience. Good Luck!