Unless your truck has had unusually bad maintenance or extremely high mileage, I can almost guarantee your oil consumption has to do with the valve seals. This is very common on the 3.0 V6 engine. If you do a google search, you'll get lots of info.

My 91 LWB LS had 93K miles on it when I picked it up last fall and she was burning. I mean smoking up quite a bit at a stop light, I was sick thinking it needed new rings or whatever. I put the no-smoke gunk in there with some 20w 50 oil to get it to pass emissions. When I had the cash I had my mechanic replace all the valve seals at the cost of around $700 with a few other maintenance issues and I now run 10w 40 with absolutely no oil burning. I'd look into it anyways.