So I've been told many times that its a good idea to change out my rear axle in my 71 coupe with a 9 inch explorer rear axle. I'm not to familiar with the axles and gear ratios in them yet can anyone explain why its a good idea? i really would like to learn more about different options so i don't mess up my first restore, I've been following all the good advice I've been given so any advice about anything i can do to add a bit of power would be much help.

 

OK, you need to stop taking advice from that person. There's no such thing as an "Explorer 9" rear". The Explorer has an 8.8. Completely different construction than the 9".

If your car originally had a 351, even a 2V, you have a 9" now, which is a superb axle.

So, what axle do you have?

The rear axle adds zero power to the car. Changing the gear ratio can make the car accelerate better, due to advantageous gearing, but you sacrifice top speed and fuel economy to get it.

You can always change the rear axle ratio in your 8" or 9" rear.

So, what axle do you have?

 

In addition to the advice given by 2+2GT, you can add a limited slip. This is not cheap, but it is an "upgrade" option.

 

Easiest way to tell a 8 inch from a 9 inch is try putting a socket on the lowest bolt to the ground.If you can get the socket on its a 8 inch if you can't get it on its a 9 inch.Both axles are more then enough for the avg small block you can change the gear ratio and add a lsd and disc brakes if wanted.And i believe the explorer 8.8 is too short to fit a 71-73 and not have the back wheels look sunken in the body.