Hello everyone, this is my first reply here, I just signed up. I have been stalking this Forum for quite some time, and mainly the posts regarding gear changes.
When I bought my truck new, I looked all over for a 4:10 geared truck, but had no luck. I found the perfect truck, but with 3:73's, so I figured I'd give it a shot. It drove fine and pulled ok on flat ground, but it needed more. I was mostly convinced I needed gears after months of reading forums, but ultimately decided after a camping trip to the Ichthyosaurs State Park, in Nevada. My toy hauler is a 33' bumper pull, weighs in around 10k when loaded, and my truck is detailed below. On that trip, I was pulling a grade up out of Gabbs Nevada, had a decent run at it, and was letting the Hemi eat. Halfway up I was down into 1st gear, it was miserable. I tried to push it to second but once it shifted, it bogged and I was right back into 1st. I ended up slowing down so the engine was at 4k RPM's for the remainder of the grade. My wife had that disappointed look on her face, and I'm sure I did too. My mighty Ram was not so mighty. Worse was it ate through my gas which did not give me enough to pull the trailer back to civilization. I had to unhook the next day and take a day trip to Austin for fuel. That worked out, because we took back roads, which led us to a sweet little creek to fish.
So enough with the story, I pulled the trigger two weeks ago and had my truck re-geared. I went with AAM 4:56's for my stock tire, stock height truck to replace my 3:73. I had Driveline and Gear Service, in Sparks, Nevada, do the work for me. They use factory AAM parts and did have to replace the front carrier assembly to accept the 4:56's. It took them 2 days to complete the job and it cost just over $2700. No whine, no funny noises, and a 12 month warranty. I recommend them if you are close.
http://www.drivelineandgear.com/
My thoughts are Ram should be building these trucks with 4:56 axle ratios. They might have their reasons on why not too, but it drives like I think it should. I know I have a large displacement Hemi with a good amount of torque now. Its quick, well mannered, and a blast to drive. My gas mileage went up on my daily commute which is mostly city driving. I am currently just under 14mpgs in the city, based on the dash readout, when before I barely broke 13. When on the highway, I notice the MPG reading to be high teens, but I haven't driven far enough on the highway to give you decent data. Running 70 mph on the highway, in 6th gear, my RPM is at 2000. One thing I expected to see more was ECO mode but it still isn't on as much as I'd like. Pulling the trailer now is far less stressful. I don't have to ring the Hemi's neck in 1st to make up for the ridiculous gap between 2nd gear. That extra leverage the 4:56's give really get things motivated now. I have yet to pull a big grade at speed but should be heading out later today for a trip.
I want to stress this to those that are thinking about re-gearing, or are planning to purchase a Hemi truck. It will never be a Cummins powered truck, no matter what we do to them. I have had 3 Cummins trucks over the years and my Hemi will never pull like them. With that being said, I am glad I made the switch to a Hemi and don't think I will ever go back. Daily life with my 15' Ram 3500 with the Cummins was terrible. It had horrible drivability and too many issues that came with the complex emission systems. Another thing to consider is the price of gears and are they worth it to you. I pull my trailer a lot, in Nevada which has the most mountain ranges in the US, 150 of them I think, and I swear I'm always pulling into a head wind (Utah sucks and California blows). For me, they are absolutely worth it, I would have paid more. I also love the new driving characteristics. It is more responsive and quite fun to drive. I hope this helps you in your decision and good luck....Mopar or No Car!!!