That might have something to do with the 80e.
With my 60e and running same tire size as you, I'm at 2150rpms at 70mph.
Love the way the 4.10s help this turd pick up and go. Almost wished i've went to 4.30 or 4.56 gears.

 

I went from 3.55s to 4.56s in my 06 quad cab Hemi ram and it would get 18 mpg on the highway spinning 2,700 rpm @ 85. Slowing down to 70 mph @ 2,200 rpm would pull an honest 22 mpg. 4th gear, 70 mph @ 2,500 rpm was a great gear to tow with on the highway although a Hemi Ram PCM is programmed to downshift from 4th straight into 2nd prime, bringing the tach to 5,000 rpm @ 70. With the APS 2,800 rpm converter and 265/265 comp cam that was in it, it would anhilate the tires all the way through first gear and often break the 305/50R20s loose in 2nd on the street. On a well preaped track, in good weather, full street trim it repeatedly ran a 13.59 @ nearly 99 mph with some tire spin off the line.

I went from 3.42s to 3.73s when I swapped from a 10-bolt to a 9.5" 14-bolt in my Express with the 5.7/4L80E. With the shallower 80E OD and 30" tall tires, the RPM climbed ~200 rpm at 85 mph, from 2,400 up to 2,600. Highway fuel mileage was unchanged, I saw a slight improvement around town and use a little less throttle to get rolling. I plan to move up to 4.10s before long though.

 

wanna swap rear gears rob my 3.42 for ur 4.11s lol

 

My ecsb had 3.42 then switched to 3.73. I was happy until I added the blower mpg sucks. Thinking of going back to 3.42. Anyhow being n/a 70 mph with 30.6" tall tire behind a 60e I would be 2000rpm ish , it never had to down shift for hills it picked up speed nice without downshifting.

 

Jumping one ratio will only barely be felt. I really like 3.90s its the highway mpg of 3.73s and the bottomend of 4.10s. Going from 3.42s and 275/55-20 to 3.90s is a nice difference. A buddy of mine has 3.73s and mine feels surprisingly lighter on the throttle.

 

With a 32" tall tire, I loved 4.56s....With the 30" tall tire on my Express, 4.10s will be very similar on the highway althoug it will be taller geared 1st and 2nd.

http://www.youtube.com/watch?v=_zESf9qHpS0

My Titan is also very fun with its tow package gearing. With the ultra low 3.89 1st gear and only a .83 overdrive ratio in the 5spd it acts like a 4L60E with 4.10s and an extra gear between 1st and 2nd. All the gears are closer together as well.

http://www.youtube.com/watch?v=4_nSTfZYvtQ

 

was on the highway today and @ 80mph the tach is about 2800rpm's I checked the speedometer to see if it was off any and at 80 its 1mph off actually doing 81mph