LT1 thermostat leak

Hey guys, I have '96 LT1 In my '69 Camaro, I have a leak at the thermostat outlet. It has a new water pump, thermostat and seal, I have tried taking it apart cleaning every thing, I then did a pressure test and it is still leaking! There is a little bit of coolant around the base of the outlet and when you "rock" the outlet back and forth you can see it move, definitely not sealing. Does any body have an Idea? Any help would be great!! Thanks!!:banghead:

Check the housing for cracks. The aluminum tends to work harden and crack from engine vibration.

I will check it out thanks!

did the presseure test come up right?.. should be bout 12lbs check for cracks also around threads on the block

I checked every thing out and there where no crack's. I made a gasket to go around the o-ring and seal the out let to the water pump, It work's great! Thanks for the input.