So finally drove my truck for the first time in a month after rebuilding the tranny, then putting a new rear end (fronts getting replaced when lift goes in). Boy what a pain in the a** this has been, but I gotta say it's reved up a little more than I like, 60mph is 2100rpm and it's loud. After the 6" lift and 37's it should be better. Hopefully 1900rpm at 60 I can live with that.

 

Pulling 22k pounds your engine will be happier with those couple extra rpms anyways. Pulling 20+k with my Cummins on 33s in 5th (automatic) at 75 or so I'm just over 2k with 4:10s if I remember right. It was too low in the rpm range in 6th for pulling.
I vote run it! The 7.3s like pulling well over 2k rpms

 

The 7.3 can pull at over 2000 but there is a point where you are just wasting fuel. If you are at 2100 rpm at 65 you will be around 2400 rpm at 75. To high in my opinion unless you are constantly towing 15K or more. For highway cruising my 7.3 likes 1800-2200 rpm, towing or not.

 

Also a 22K goosneck is one heck of a trailer to tow with a single rear wheel truck. I don't like being a weight police as long as you are only a couple thousand pounds over, but in your case you are about 8-9K overweight, and your rear axle is probably overloaded by 1000 lbs, no wonder you had problems.

 

That's kinda where I'm at, it feels like a old obs wound out just to go 60-65 and fuel limiter at 85 (don't know that for a fact) but I'm hoping after the 37's it will drop 200rpm and be 100rpm over where my truck starts pulling hard. Probably why i towed at 65 all the time 1800 rpm and seemed to be happy there. So now if it all goes good I can kick it down to 60 so my brother and dad can keep up on our hunting trips!!! If I constantly towed 100% of the time the gearing would be perfect but the mix I do 4.10's would be much better on 35's for a good mix.

 

If you have a tune then there is no limiter factory cut out at 95 or so but a tune removes that. Also unfortunately I don't think you will see a 200 rpm drop going to 37s more like 100 rpm, but that will still help, also what is the speed limit on the highways you tow on? If it is 70 I wouldn't recommend going only 60, you'll just hold up traffic.

 

That's where I like my truck to just on the lower end empty and the upper end while towing heavy. My normal load that I tow allot truck and load is 23k so it's not to bad, most I tow the truck and trailer going across the weight station is 31,250lbs which I do twice a year for a 100mile stretch (fertilizer) other than that Im towing my tandom that's 6k or my tripple 40' at 12-13k. How it was before I was in 4th while in the hills, 3rd in some spots over the passes, and 5th on slight rollers, flat, and down hill which worked well but wish my 4th was a little lower so I didn't need to drop to 3rd. Drove it again yesterday and I'm getting more used to the rpm, and actually putt a little power down without the clutch trying to slip (still in the break in process). Talked to my buddy yesterday which has 4:30 gears and 37's which I didn't know and he said jumping from 35's to 37's made a huge difference in how fast he is able to go on the freeway 70-75 his truck is in the 2-22k rpm range which where he was 2300-2500rpm range prior going 70. I've rode in his truck down at hammers this last year doing some parts runs and i didn't notice a difference between mine and his really besides power. So I'm thinking I'll run with it and see how I like it after it's all said and done, thinking from what everyone has said and my buddy I'll be happy with it!

 

Here's mine with 4.10s and 285/75

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Attached to this post is a gearing calc for the 4R100 that will let you see what speed, rpm gear based on the gear ratio and tire size.

 

Try this one Gear Ratio Calculator