My Ranger's tach says the same. 2500 in 5th and 3100 in 4th. That's the way the trans is set up. The speedometer runs off the trans. I was talking about actual road speed though. Are your numbers still correct when referring to what a GPS or a radar gun would say your speed is?
My stock Ranger with it's 3.45 would run those RPMs at 65 mph accurately, with 215/70-14's.
If my calculations are correct (I used the calculators in this site's tech pages) if I drop to a 3.73, I don't really know what my RPMs will be but my road speed will be slow by about 5 mph. But I can compensate for that with 235/70-15's. My idea is to go with the bigger tires, the 3.73 axle, and it'll run like I've got my stock 3.45 if I'm running the bigger tires. However when I pull something heavy like my camper, I can put my 14's back on the truck and run it at "70 mph" which will be an actual road speed of 64.75 mph. Or 3000 RPM, whichever is slower.
For some reason my 2.9L seems to vibrate a lot above 3000 RPM. The rear seal is leaking and the trans is also leaking from the top, so if I keep it under 3 grand, I won't have to add as much oil. It's a PITA adding fluid in through that little hole on the side of the trans too.