Drivetrain Help Choosing An Irs

I have experience with the cobra IRS. If you're going to buy a used one that's not in a car running it would be best to get the rear gears rebuilt. With it out of the car its not terribly expensive. Check the axle boots for rips and cracks. The only way you know for sure what you have is to open if up. If you go that far you might as well build it... 3.73 gears and such. Try to get all the brackets and bolts. The rear shocks are a plus. The cobra shocks take a bigger bolt that goes through the lower control arm. Buy the higher mileage one out of a non wrecked car with the brackets and good axles. Replace the bushings, wheel hub bearings, and put a gear set in it. If you change the gear ratio from what your original rear had you'll have to recalibrate your speedometer.

Mileage doesn't really matter...I remember people breaking half shafts with only 20k and a lot of bolt on horsepower. You do want to stay away from rears out of wrecked cars. With so many bends in the cradle its hard to tell if it was tweaked. I always replace the hub bearings because they're cheap and easy to change. You can spin them and check them first. Age or mileage doesn't make a difference with our cars....its how much abuse they've been put through that matters.