Why? it isn't that big of a deal. Just that some shops don't do it, and a driveline shop will do a better job. I both of mine done for $86 a piece with balancing. I don't have the double cardan, but it should be under $150 to have the front shaft pulled and done...

 

they checked the t case and it was leaking out of a gasket omn the front side. but very minor, they checked the fluid level and topped it off and she looks good. total cost::: $0

 

The capacity of the tank is not relevant in figuring your milage.

Here's how to do it without knowing capacity:

1. Fill your tank and reset your trip-odometer to ZERO Miles. You might want to really push the gas in so you're nearly overflowing to make sure the tank is completely filled... all the way full.
2. Drive either city/highway or both until you're ready to refill.
3. Refill your tank but take note of how many gallons and 10ths of gallons it takes to bring it back up to completely full. Again, push in the extra gas until it's nearly overflowing just like you did the last time - so you'll get a real number.
4. Note the number on your Odometer (which is how many miles you've driven since the last reset/fill-up)

5. Now divide the number of miles you drove (say 240) by the number of gallons of gas it took to bring it back to full. Let's say 14.83 gallons. In that case your milage would be 16.183 mpg. If you're driving my car however, it's more likely you've driven 140 miles and bought 11 gallons of gas to do it. (My LR3 is a touch thirsty!)

Hope this helps. BTW: the usual capacity for the tanks in the new ones is about 23 gallons total. The manual may say 22 or 21 but the parts guy at the dealer told me it was 23 on the box the tanks are shipped in when they need replacements.

 

I think my D1 is 24.6 gallons. I'm usually putting in about 20-21 gallons each time I fill up. I'm getting about 12 MPG around town (240 miles between fill ups). Which is up from about 10.5 MPG when I first got the truck. I've been running Lucas octane booster and and upper cylinder conditioner and changed the plugs. Will do the wires, plugs, cap & rotor again soon.