Towing rating and power aren't synonymous. It's more to do with vehicle curb weight, stopping power, and suspension/frame rigidity.

​​​​​​torque at the wheel is anywhere between 20 and 40 percent less than at the flywheel. Disco torque at tires is probably 200ft/lb or less. It is good up to about 2,700 rpm, but the factory converter stall tends to be around 3000 rpm under load, the one dead spot in the torque curve.

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Point taken. But let me describe actual experience. Again it's a 2002 4.0 ltr and engine is good, new heads, timing gear etc etc. I do have a full arb bumper and winch and somewhat larger tires on.

1. On a decent grade, with a full tank of gas and no tow vehicle, it will always shift into 3rd to make it.

2. With a 3000 pound trailer, it shifts into 3rd immediately and on a long grade, down to 2nd gear and 38 mph is about the best she can do. On a longer grade she heats up to 210 degrees or so even though I have a 180 tstat.

I don't mind going slow and I love my D2 and don't want to have to change.

Problem is, I'm afraid I'm tearing it up when I tow. Any opinion?

 

Contrary to what everyone says about towing it doesn't wreck the truck if used sensibly. How much larger are the tires both in width and diameter? you are also carrying quite a lot of additional weight at the front end with the steel bumper and winch. It does sound like the truck needs lower gearing to address your problems but that will also affect your speed in every gear and top speed when not towing and inevitably cost you more in fuel. It also depends on your ratio of offroading vs highway, if it's 90% offroad and 10% highway it will not cause you problems but if it's 90% highway and 10% offroad you will be fishing for another gear or travelling slower or at higher rpm. Of course if it's 100% highway just reinstate the original bumper and sell the steel bumper and winch as you don't need them or the larger tires etc. A 4.6L untuned engine is only 15% larger but no doubt the additional torque will be probably be 5-10% more and the additional cost will be extortionate for the extra gain. IMO the 4.6 has far too many issues to be considered before thinking of changing engines just for towing a trailer, of course, unless you are seriously rich.

PS: before making any decisions do a spreadsheet of the pro's and con's with costed options which may help with any decisions and then find out the real costs as everyone is usually more optimistic when making decisions.