[csw]

6t8stang, it was just the rear light. I pulled both and swapped them from side to side to make sure it wasn't the plug, and it looks it was the bulb. Put it back in, and both are now working correctly.
As for the exhaust problem, Going take Cashburn's advice and re-torque intake manifold bolts although the consensus with most everybody I talk to is re-torque and do a leak down test.
I'll keep you posted on what we find out.