If you're thinking about purchasing a Dana Differential for your Jeep there are a few things you need to keep in mind.

1- Research the DANA product number you require.
2- If that is not possible refer to your local Jeep club, the most likely will be able to help you with your questions.
3- Pricing is always an issue some used or reman differentials may not worth the risk if you know what you are shopping for.
4- You can always ask the pro's at: -- www2.dana.com/EXPERT/expert.htm -- if you can't find the information elsewhere.
5- Axles can be modified to fit your vehicle one good site you might find interesting is: www.jedi.com/obiwan/jeep/mods.html 
6- Shipping rates can be expensive depending on your gegraphic location, chances are that if you have a cheaper rate than the seller's, you can always ask them to ship with your carrier, or arrange pickup at their location.
7- Make sure the item you purchased is the item you require to avoid uncomfortable experiences with not needed returns or exchanges that will only make the transaction even more pricey.