Guy in MN has a 77 440 for sale in the Vintage Sleds classifieds. Not sure how different it is from a 76, guess they only made this model 2 years. About a 5 hour drive for you, $300.
The sled was on page 11 of the classifieds but these things move down the list pretty fast so hard to say where it is now. If you go to the Vintage Sleds classifieds and search on "prestige" it should come up.
Otherwise, the seller lists his number as 3205832078 and email as xxxdolbern@emarqmail.com (removing the "xxx"). The sled is located in Stewart, MN, west/southwest of the Twin Cities.