The 3.21 gear ration wouldn't have made the swaying any different... Moreover, the POWER to pull the trailer up the hills here in texas won't be affected either. The GAS Mileage will.. but the actual ability to TOW the trailer behind you isn't altered. I'm worried when people ask questions like this, they use google 2 years from now, and find threads lke this. It's extremely important to understand the importance of a gear ratio. If the truck is capable of towing 8k at max payload ( example number here ), then that's what you can tow / haul. Having the smaller gears doesn't give you a truck with a smaller motor, you still have the same transmission, and you still have the hemi beast under the hood.
If you're okay with better gas mileage, and a lower max payload, the 3.21 isn't a bad thing. I only bring this up because your choice in saying " I only had " , as if it were somehow preventing you from towing what you had.
Maybe I should have clarified that I also had tires taller and wider than stock (295/60r20s - 34"). The 3.21s didn't limit my ability to pull the trailer. They definitely didn't do anything to improve the towing, that's for sure. After the lift and tires, the truck already felt sluggish compared to stock. From a dead stop, it pulled great thanks to the 8 spd. But once I got up to about 4th, the trans seemed like it was always searching for the right gear. Like I said in my post, it pulled fine on flat roads (like driving down to the coast).
When I talked about towing in the hill country, it was the suspension, not the gears that I talk about, althought again, the gearing did play a factor. Some of those roads up there are 60 mph and the slower ones are still 50 mph. I never did 60 mph, and even felt uncomfortable at 50 mph on most of those roads. Again, though, the transmission always seemed like it was searching for the right gear. Having 3.92s would have given the engine a few more rpm in the powerband to hold gear better.
Right now the 3.73s with my 295/65r20s (35.4") and six speed is too tall. That big 6.4 Hemi feels sluggish without the trailer behind it. More so with the trailer. BUT man, I love the stock trailer brake on my 2500. It works better than the aftermarket one I had on my 1500. No more goofy tow mirror like the ones I'd slip over the stock 1500 ones. The rear doesn't sway or bounce anywhere near as much as the 1500 did.
My point is more that if he's towing heavy multiple times a month and stacking those trailers, he may just want to go for the 2500. If he gets the 1500, he spends money on the tow mirror, then he might want to upgrade the rear with air bags because the suspension might feel "squishy" with that weight, then he might want to go with shorter gears anyways to help the transmission hold gear better.
yillbs, your sig says you have 35s and a lift, so did I on my 1500. You said you towed just fine with it once...
I'm no expert at towing, I only had my 1500 for 2 years with a 4" lift & 34" tires and towed my travel trailer about 8-9 times in those 2 years (minus the day I picked it up and the days I took it back for a warranty repair). My 2500 has a 3" lift and taller tires than I had on my 1500. I've only towed the trailer twice with it, but I can tell you there is a big difference towing with that 1500 and the 2500.
The OP might be happy with the 1500. He'd be saving $$$$ daily in gas and that great deal he found. As a daily driver the 1500 wins hands down. I do miss that smooth, plush suspension for daily driving. I was just giving an opinion based on my towing experiences. It was an expensive lesson to learn getting the 1500 then going to a 2500 2 years later. And the OP will be towing a whole lot more than I ever did.
Again, just my $.02. The OP can take it for what it's worth. I'm glad your experience towing with your 1500 is different than mine was.