It depends, Ruger may have used up some spare parts and blued Sixes may have had either blue or stainless hammers and triggers through the early 80's.
As a rule of thumb, usually the "scalloped" recoil shield blue models will have the stainless hammers and triggers.I have an 82 blue Service Six with the smooth faced stainless trigger and hammer and it is a round recoil shield model, so there are some "transitional" or cleanup guns out there.
All of my blue Sixes with the round recoil shield have the blued hammers and triggers.