I'm looking to get improved gas mileage on my 97 Wrangler, and may consider installing lock-out hubs. Will the cost of parts and installation be worth the improvement in gas mileage? Will the entire axle need to be replaced?
Changing the hubs sounds like a good idea for improved fuel mileage; they will disengage the wheel from the differential and make the front wheels free wheel improving fuel mileage.
But it also depends on your driving habits, running condition of the engine and transmission and the area you drive in.
If you are in a mountainous region or go four wheeling a lot it will change your mileage per gallon. I'm sure you are aware of that.
From what I understand is that when you need four wheel drive you need to manually lock them in, the driving feel will be different than you are used to.
The wheel hubs usually come with detailed instructions, if you are doing it yourself.
If you are going to have it done by a mechanic, choose your shop carefully and by reputation.
The price will vary from shop to shop.