This is a pic of a light blue-colored 1980 Mercury Colony Park Station Wagon. It was used by Bosley and the Angels in a few episodes of the fifth season. This pic is from Fifth Season Episode 1 (the 2hr season premiere "Angel In Hiding"). This should get 3 stars.

http://www.imcdb.org/vehicle_685450-Mercury-1980.html

Was "Colony Park" the exact name for this model, btw? There are no others 1980 models listed under this name in the site.

Yes, Colony Park was the name of the station wagon...this was the Mercury version of the Ford Country Squire--which was actually considered a step up from Ford. I don't know if Marquis was included with the wagons...but it was a Colony Park. Colony Park station wagons were made up through the early to mid 1990's. I believe this was a 1980 Colony Park--as pics I've seen of others match and this was filmed in spring/fall of 1980.