That does sound quite high. At 110 km/h I'm at about 1750 Rpm with 3.55 and 285/75/16's. Rpm's are lower because of my larger tire size, but still, you should be getting better than that by a long shot. Either your OD isnt engaging or maybe your tach is off like SilverSS suggested.

Are you pulling anything or carrying a lot of weight in the truck?

 

ya im at 1900rpm at 70 3.55 265/70/17.. i just got my shift kit installed turned out i had a broken o/d spring but when it broke it still worked right. but the guy said that my o/d would of went out eventually

 

Wow, 3200? Something is wrong. My 2500 with 4:10's at 80 mph with 265's barely get's to 2500 rpm.

 

That would explain the crappy gas mileage......Now, I wonder what could cause this? Any ideas?

 

I don't know enough about transmissions to tell you. But it sure isn't going into OD. Most likely what you feel is TC lockup. And when you turn OD off it's just kicking out of lock up not OD itself.

Have you scanned it for codes?

 

No codes. In fact, while driving, I had MTG 2500 connected and glanced at it occasionally. Showed to be in OD, TC locked up.....

And 8uzzsaw, minimal load - three adults and luggage for one night. Nothing in bed.

Got pretty good at dropping tranny in just under 2 hours, but don't know what to look for. More research I suppose. 3200 rpm would explain gas mileage if it should be about 1000 rpm less at 70 mph.

 

3200 rpm at 70 mph on 3.55!! wow.. im not sure what could be the problem. i know at 70mph with 4.10's and 285's im at about 2400 or so.. I cant remember what it was before i swapped out the 3.55's though.. Seems high

 

I wonder if the wrong TC could cause this to happen? The box had the right part number on it, but TCs are seldom marked with part number....either that or I may have to drop it and pull OD off and check it out.

Guess this should be in tech section instead of general discussion. I was hoping that 3200 was normal .....

 

Doesn't matter what the scanner says. You need to push the OD button, if OD is working, it should drop out of OD and RPMs should go higher. If there is no change when you push the OD button, it's not going into OD.

 

Holy $hi7 i got almost 12 mpg in my truck.....i have 4.88 37s and i sat just over 2400 rpms @65