So let me start off I got a new truck 98.5 reg cab long box 4x4 with the 360 145,000 miles has 4.10 and decent tires for $600. Anyways upon first start up its like a mini seafoam blue smoke after that initial any time you punch it blows a decent cloud. I did the plenum and PCV on my last truck but that was 3 years ago can they cause this kind of usage or should I be looking more motor related valve seals, rings, etc.?

 

I would be guessing plenum, but since it's a $600 truck I wouldn't doubt the valve stem seals being gone and/or the rings not being far behind them.

Smoke on first start up is valve stem seals (not to be confused with guide seals), constant smoke is guide seals or rings, and smoke when you're getting on it is usually a blown plenum.

 

Are the eBay plenums still in existence or did I miss out on that gravy train

 

I didn't get any smoke when my plenum was bad..
Just a clogged cat.

 

The exhaust is all hacked up there's no cat anymore but when I get on it it's consistent and it didn't do this when I first bought the truck

 

Its pretty easy to check the plenum. That's where I would start.
Also, I didn't see any eBay plenums when I was looking (about 2 weeks ago).

 

Sometimes I think the cats filter the smoke out of the exhaust, hence why they clog. But that is just one man's theory.
BOOM

http://www.ebay.com/itm/DODGE-JEEP-ALUMINUM-PLENUM-PLATE-BELLY-PAN-318-360-5-2-5-9-MANIFOLD-REPAIR-KIT-/251368846182?pt=Motors_Car_Truck_Parts_Accessories&hash=item3a86c03366&vxp=mtr

 

Alright I'd like to change the symptoms a bit it only smokes on first start up really bad after the truck has been driven earlier I started it up drove it 10 miles everything was fine no smoke or smell shut it down for about a half hour started it back up instant oil burning smell through the vents and smoke out of the exhaust

 

Bad valve seals, worn guides, and still need to have a look at the plenum.

 

Makes sense to me. My plenum was bad, and I didn't see any smoke so it had to be going somewhere.