Had our 2008 450 since Feb 07. Thought about an auxillary tank but cost and hassle has deterred me. We get 200 miles with the stock tank (4.88 gears) and in 75,000 miles have only been close to running out a few times (did run out once..10 miles from destination). The only places we were concerned that a fuel stop could not be found was in northern Ontario.
Other considerations are being able to take advantage of lower fuel prices or going longer before refueling. I wouldn't worry about needing extra fuel to get to the next gas station...its a non problem.

Well, I wouldn't be without my extra fuel tank. It removes the probability of being forced to purchase fuel at an out of the way place with bad access. bad fuel or higher than normal prices. Ours is only 36 gallons, and is a transfer tank. DOT regs do not allow a "non DOT approved" tank being a fuel source to an operating engine. For some idiot reason. Anyway, most of the affordable tanks are listed as transfer tanks. I refuse to haul so many tools that I need a tool box in the back of the truck. Since the pickups have so many computer operated systems, I am lost anyway. I do carry enough tools to perform minor (read minor) repairs to either the truck or trailer. A cell phone does not take up much room, and a business card with an ERS number on it is very lightweight. I'm kinda like Fred, a small toolbox is easy to get at in the basement.

FWIW, in 4 years and over 40,000 miles towing, we have NEVER had a problem finding a service station we could fit in when we needed it while towing.

Needless to say, we always start the tow with a full tank. 99% of the time, we are at our destination before we are even close to needing fuel.

You should really try it first, you can always add it later.

Hey Terry:

In this “opinion” department, here is ours.  What works for you may be different.

I put a 50 gallon Transfer-Flow tank (http://www.transferflow.com/) in the Chevy 3500 day-one and have loved it.  It is just the right size and allowed a big heavy duty “stuff box” from Wally World ($50) to be installed (sit) between the tank and the hitch.

Here was my thinking and it still works for me after 4 years:

First, the Transfer-Flow tank automatically “pumps” into the OEM tank via a small pipe into the OEM iller neck.  If the Transfer-Flow pump or control system fails, the OEM is still there and unbothered by the failure.  No cutting or modifications to the OEM fuel system.  A very good thing IMHO.

The tank is DOT legal.  I won’t argue what is and isn’t legal. I just know this one is legal and is safe IMO.

It is not that I don’t want to stop often.  It is that I don’t have to stop where I don’t want to for fuel.  If we get into camp a bit later on a particular day I don’t have to worry about “getting fuel” the next morning or whenever.  The 50 gallon tank gives me 84 total gallons and that make it really comfortable to look for fuel on “my terms.”  I also have the very nice “how many gallons left” readout - “Trax-II” Transfer-Flow system - in the cab - amazingly accurate - and know for sure my fuel situation.  I just like that.

(You’re free to run or keep the aux tank “dry.”  You don’t have to have any fuel in it for the “off season” or whatever reason.)

Personally, I don’t care for combo fuel and tool tanks / bins.  I looked at this real hard and I feel the space you get in the combo for “tools” etc. isn’t as good as my big $50 Wally World bin that I “steel-cable” to the truck.  That’s just a preference.  I do carry most tools in the truck because I will always have the truck where I am.  Don’t want to need a tool when roaming around and it be in the rig.  ‘Just personal preference.

BTW, this tank and bin fit totally below the bed top, so nothing is sticking up to get in the way of anything, including the 5’er pin box in a tight turn.

Again, I got this put in “day-one” and have really enjoyed the flexibility it gives Linda and I when traveling and the peace of mind that “low fuel” has, thus far, never been a question.

The web site is very complete and helpful.  I do recommend the product if it meets your needs.

My 2 cents

Bill

I also am looking at the toolbox/fuel tank combo. For the fuel just to have a piece of mind. When we went to SD last year we took all back highways and the prices of fuel varied by up to .20 per gallon. Just around here, a 10 mile drive can save me anywhere from 10 to 12 cents a gallon. Because we are determined to find a way to also haul our motorcycles, that would be a place to store our tie down straps and care products for the bikes, the truck and the 5ver. I have found a couple of places in Texas that seem to have some good pricing. One is www.pickuptrucktoolboxes.com

Our dodge has an OEM 36 gallon diesel tank. I get 9- 10mpg towing. So that gives me over 300 miles for towing. As stated above I always start out with a full tank. However, for piece of mind, I carry two 5 gallon diesel fuel containers in the bed of the truck. I generally don't like to travel over 4 hours but It's good to have the spare fuel on hand if needed. For me, I don't think that carrying 30 plus extra gallons of fuel is cost effective given the extra weight I would have to haul around.