W. Anderton

R. Salonek

J. Feetham

R. Reid

B. Wills

We simply drive most of the time with it in direct and when faced with a hill or a headwind, or for better performance is city traffic such as Atlanta, Nashville, or Indianapolis or any of these like situations, we simply select the underdrive position, and just go about our business as though we had picked up an extra 50 or so horsepower.

We have the 5.9 (359 cubic inch) Cummins diesel, and normally empty we average 23.8 miles per hour. In city traffic, with the underdrive engaged even when empty, (for better performance and control), our mileage did drop 1.8 mpg. However, on three different occasions, pulling the same model 5th wheel from Elkhart, IN to the same location in NH, the average mpg actually increased when we used the underdrive while loaded. Normally we averaged 14. 8 mpg "pulling" prior to installing this unit, but it was extremely difficult to maintain speed with normal hills, even with the Cummins. By the way we have had 5 diesels previous to this one that we installed the underdrive unit on so we have a real good idea of what we are up against. Now with the underdrive installed our average with using it and letting the automatic overdrive transmission select when to shift as necessary, our mileage has actually increased by 1.4 to 2.1 mpg. I think this is due to the fact that the throttle doesn't require being "mashed" to the floor and the tranny being out of OD in hilly travel or windy travel. Folks actually think we have installed a larger engine!!! We have nearly 200,000 trouble free miles on this unit, and it has not given us one ounce of trouble. It shifts normally from direct to underdrive whether we are in New England at 35 - 40 below zero or in Arizona at 110 in the heat.

Now let me give you some operating advice. We were warned or told for a better choice of words, and it is well documented in the literature, that there will be a rather loud "clunk" when you shift in or out of underdrive. At first it bothered me, and then we learned to shift the automatic OD transmission to neutral and then select the auxiliary transmission to either position and then place the main truck transmission back in normal OD. The "techs" that installed ours stated that they were well aware of this but declined to tell folks about it as they did not want to be blamed if someone tried this way and inadvertently placed the main transmission in the wrong gear, which I can understand. But, my wife normally just shifts it in and out by simply selecting which position she needs without worrying about the "clunk".

Basically, it is a real good investment and it is one of the few products that we have purchased in all of our years of delivering boats and RVs that actually outperforms what the sales folks tell you it will. Your truck will really pull just about anything you hitch it to with this unit installed. An added benefit that we have noticed is that it is really great when pulling in slippery snowy conditions, especially along the NY Thruway when the lake effect snows continue and you have better, I mean really way, way better control with the extra rpms, and the slower speeds in 4 wheel drive high position. Four other couples with whom we work with out of Elkhart IN have installed it as well, 3 with Dodge diesels and one with the Ford power stroke diesel and their performance is equally as impressive as ours. Basically, I believe it is because the engine doesn't have to work as hard to keep the "load" moving when the underdrive feature is engaged. Bear in mind that we lose approximately 8 to 10 mph for the same engine rpms that we would normally be operating with in a diesel, and I personally don't like to go beyond 2250 rpms with this engine even though it is normal to go to 2500 rpms or better. That is the old fashioned trucker in me from the big rig days. But, hey, I would rather get the mileage and lose a couple hours and enjoy more scenery, especially at fuel prices as they are today.

In short, I don't think you would go wrong in installing this unit in your Dodge. If it performs half as well with the gasoline engine as it does with the diesel, you can't go wrong.

J. and D. Farnham

Update: Late 2005
Just want to let you folks know that the underdrive we installed in a '96 Dodge Cummins dually is still operating flawlessly with over 400K miles on it. Our son is using it to pull a cattle trailer in upstate NY and loves the fuel mileage and the performance. We thank you again for a great product.