Yes, Another Manual Tansmission Question!

They do not in most cases with a 2.7L 4x4. Your RPM gauge is not a fuel use gauge. If you are moving down a highway at 2000 RPM and I sit in my driveway and rev to 2000 you will run out of gas sooner.

You are 2wd and the OP asking the question is 4x4 access cab. He explicitly asked "I am trying to get the best gas mileage without hurting the transmission." Everything with this motor has to do with load and a 4x4 system has much more loss then what you are driving. You will probably see a lot different results with 400+lbs less weight and a different drive-train. These engines/manuals with 4x4 perform much better at a higher rpm and provide better overall mileage then following the low rpm shift method of the v6. It is also bad on the bearing/rings to lug the engine and will probably be leaking oil past the seals down the road if done constantly.

The answer to his question is: just a low enough rpm to not lug the engine no matter what gear he uses. 1400 is low for any gear and lugging with a 4x4 Access cab 2.7L engine.