given all this i think im gunna stick with the 3.73s its got. my mon-fri driving is mostly in town with maybe 5 miles at 55-70...but on weekend when i go home (college student) i do a 100 mile one way trip at 70+ the entire time.

as for 16mpg spinning 37s im ok with it but i just want to get some better numbers if i can. im sick of having to fill up once a week and watch $80-$100 fly out of my wallet like its nothing

 

Nope... No need to lock out OD...

Only time I will lock it out is if its hunting for gears.

 

I just towed my trailer to Kalispell over the weekend, and I couldn't run in O/D all the time, the egt's would climb so fast when the truck started to climb a rise and the tranny didn't kick down soon enough. So I was constantly manually locking out the O/D.

I'm towing 12,000 lbs running 35's w/3.73's, your towing 25k running 37's w/3.73's (used to be 3.73's).

My truck wouldn't pull 65-70 mph in O/D without the egt's hitting 1200-1250, the road is not flat but it wasn't like I was climbing huge passes.

 

Have you checked for boost leaks and drive pressure leaks?

There is no reason you should be having EGT issues at those weighs and power levels.

Chelseas Excursion is on 37's and 3.73's and I pulled a F-250 like mine on my trailer without issues from Bend to Portland... Just set the cruise and go.

 

Haven't checked for drive pressures leaks...I do have a an up-pipe leak which I am going to address this weekend.

 

Even the smallest drive pressure leak will cause high egt's.