4.3L Vortec Smoking Bad Passenger Side

So I just had this motor replaced probably a month and a half ago, the new motor had about 130,xxx miles on it. Today I drove it across my small town on my way home, at about operating temp, no overheating or anything. I pulled in the driveway and it was smoking from the passenger side exhaust manifold. It seemed as if I was pouring oil on the manifold, that's what it smelled like. Anyone have any ideas? I checked the oil, it's about perfect as far as capacity, but it's due for a change. Thanks in advance for any ideas.

If the rocker arm cover gasket leaks, it will drip oil onto the exhaust manifold, and it doesn't take much to make a cloud of smoke.

Alright thanks. I'll start there. Any idea how much of a pain they are to change?

The gaskets aren't too bad to change. I would first check to make sure the oil fill spout is fully engaged in the valve cover as well as the fresh air intake tube. If either of these is loose you could get oil seepage and a drip onto the exhaust manifold.

Thanks, appreciate the info a lot.

So I just had this motor replaced probably a month and a half ago, the new motor had about 130,xxx miles on it. Today I drove it across my small town on my way home, at about operating temp, no overheating or anything. I pulled in the driveway and it was smoking from the passenger side exhaust manifold. It seemed as if I was pouring oil on the manifold, that's what it smelled like. Anyone have any ideas? I checked the oil, it's about perfect as far as capacity, but it's due for a change. Thanks in advance for any ideas.

Got a good warranty on it?
Oil black or brown or white looking?
How is the coolant level?
Any engine missing?
Pull plugs on smoking side and see what is on plugs.
Coolant or oil?