my 04 was dropping oil gauge pressure and then would bounce right back,I was thinking it was sensor. Well last night after work I get on the pike and only 5 minutes into a 60 minute trip the gauge drops out and I start to get a knock, pull over and shut her down,look under the hood thru this cloud of smoke and find nothing, after a phone call home I start the truck and listen, all sounds good, I start off again, about 5 miles more and the knock is back, pull over ,shut her down and call for a hook. I have only worked 12 weeks in the last 23 months so repair shop is probably not in the cards for me, more like on my back in the yard.......I'm thinking oil pump, even though I get oil pressure when I started it??? could be this dowel pin I'm hearing and reading about???