Originally Posted by Kajtek1
You are not saying why you want the gear vendor? Since you are talking about towing, it is definitely not for fuel economy. Do you have a problem with low speed torque?
Gear vendors cost several thousand dollars and they will not bring much resale value to the truck.
The 6.9 l diesel is not having the best reviews to start with.
Resale value on a 20 year old truck is not part of the equation, improving uphill towing and towing speed on flat ground is, along with keeping a vehicle they have had many miles and years of experience with.
The 20% underdrive will help the truck to tow the trailer in a higher transmission gear uphill, without overheating, and the 20% overdrive will allow for faster running on the flat ground. A 6.9 with a C6 automatic, and 4.10 rear axle, is not set up for a blistering top end.
Also, the direct descendent of the 6.9, the 7.3 Powerstroke, has millions of users driving tens of millions of miles, and an excellent performance record. The 6.9 also was miles ahead of its other light truck competition in its time.