Hey Munster man, GM Parts Giant lists it as fitting the following vehicles, hope this helps. Weird they omit the 00-05 6th Gen Monte's. I may go scavenge too, it is an exceedingly rare part. Good luck in your searches bud, perhaps "Grandpa" can fab one up in his lab for you...

Vehicle Fitment

Year Make Model Engine Important vehicle option details

2005 Buick Century 6 Cyl 3.1L CUSTOM 4 DOOR

2006-2007Chevrolet Monte Carlo 6 Cyl 3.5L, 6 Cyl 3.5L Flex, 6 Cyl 3.9L, 8 Cyl 5.3L LS, LT, SS

2004-2008 Pontiac Grand Prix 6 Cyl 3.8L, 8 Cyl 5.3L 4 DOOR, GT 4 DOOR, GT2 4 DOOR, GTP 4

 

Grandpa has been chasing Igor around for days and recently blew up his lab for the 100th time.

 

The part you are looking for was never offered on the 00-05 Monte or Impala (my guess is because it was a design GM made in 2005 for next generation models).

 

Well it was a search. But I found a deflector in a wrecking yard. It came out of a Oldsmobile Intreqe was older than my car but had the same HVAC system (heater). Opened up the cowl and there it was pulled it out and done. Right part number and everything. Herman