Yep it fits! Installed it today, I had to use a flapper wheel on an air grinder untill it fit in the bore
but it did eventually fit.
It's raining now so I'll have to wait to take it out for a run to see if the noise is gone. I put in a 180 T-stat with 6 1/8" holes I drilled in it. I let it warm up and no leaks!
My only problem now is I need a switch that makes the HHR fan come on sooner. Now it doesn't come on till 195, then it cools it right down to 180 then turns off...... then heats up again to 195, then fan.... etc....