I have the stated truck with 147,000 miles. I decided to change the gearoil on front & rear diffs and also change the oil in the manual trans. I had it in the shop to replace the center bearing unit and thought it would be a good time to do this. The mechanic wondered why I was changing the oil after I picked it up (stated the oil looked fine and didn't need changing). I just figured it would be a good idea with this many miles - until I got with the bill. Near $200 for the oil changes (not including the center bearing replacement). Wow. Anyway, the bill indicates they used synthetic gearoil. Does this all sound reasonable to anyone, besides me? Also, what type of gearoil is recommended for the manual trans and the front and rear diffs.? Thanks.