Don't know any model #'s , so may be of no help, but we replaced the original wall mounted thermostat with one from Lowes, about 30 bucks. One in a 90 Excella, one in a 93, both original furnaces. Both work great. One furnace is Suburban, the other Hydro Flame.
Region 3 , 1st VP
Go often to the house of a friend, for weeds choke the unused path........Emerson
Never pick a fight with an old man. If he is too old to fight he will just kill you........a wise old man.