Be glad it isn't a Cadillac.  The thermostat went bad in my 2000
Seville.  To replace it required removal of the water manifold and the
job was 6 hrs.  The replacement of the water pump would require the
same labor so I had them put in a water pump, new gaskets (old were
leaking), and a thermostat.  The thermostat they got from Cadillac was
bad and they had to the job all over again.  I paid $1200 for the
job.  They didn't make as much as they could on this one however.

Cadillac's are nice cars, but maintenance is expensive - Northstar
engine.

Bob
Alex. VA