Well it came on today. Didnt really notice anything with the truck that changed besides the light now being on.

Threw codes 21 and 37.
21 is the oxygen sensor is not flucuating. My Cat Conv. has been rattling a lot lately so i figure it has just came apart and is no longer within the operating efficiency range. Anyone confirm this? I plan on just cutting the shell open and gutting it and then making a MIL for the rear 02.

37 is open or shorted condition detected in the torque converter part throttle unlock solenoid control circuit. I have been having trouble as many of you will recall...could this be the problem finally throwing the code?