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**sourdough** · 02-15-2015, 12:43 PM

I've had the Ram 1500 hemi with both the 3.55 and 3.92 axles. I've not driven one with the 3.21 but I've driven older pickups years ago with axles in the 3.2x range.

You will find the 3.21 will have trouble with the load; not because of the engine but because 3.21 is simply too low for towing much. It will be affected by any headwind, any small incline and even small amounts of payload will signifcantly degrade its performance. I pulled an 8000 lb trailer with the 3.55. It did OK but a stiff headwind made it hunt for gears until I just locked it in 4th. Same came for moderate inclines. The 3.92 was considerably better and didn't hunt near as much. I didn't lock it in 4th generally but at times I did. Mileage between the two might have been 1 mpg or so...I really didn't compare but it wasn't much. As the numeric number of the axle ratio goes up the faster the engine spins at a given speed. I've never seen that as an issue. I've had a 4.10 in a 1500 and loved it. I only towed a uhaul trailer with that one.

02-15-2015, 12:43 PM	#37
sourdough Site Team Join Date: Feb 2014 Location: W. Texas Posts: 17,700	I've had the Ram 1500 hemi with both the 3.55 and 3.92 axles. I've not driven one with the 3.21 but I've driven older pickups years ago with axles in the 3.2x range. You will find the 3.21 will have trouble with the load; not because of the engine but because 3.21 is simply too low for towing much. It will be affected by any headwind, any small incline and even small amounts of payload will signifcantly degrade its performance. I pulled an 8000 lb trailer with the 3.55. It did OK but a stiff headwind made it hunt for gears until I just locked it in 4th. Same came for moderate inclines. The 3.92 was considerably better and didn't hunt near as much. I didn't lock it in 4th generally but at times I did. Mileage between the two might have been 1 mpg or so...I really didn't compare but it wasn't much. As the numeric number of the axle ratio goes up the faster the engine spins at a given speed. I've never seen that as an issue. I've had a 4.10 in a 1500 and loved it. I only towed a uhaul trailer with that one.