Great Old Stoves
Both stoves were the best of the cast wood stoves in their day. The Defiant will heat a barn, the 602 a room.
Check out:
1. ALL gaskets. Check the size online or at a good stove shop and replace ALL of them.
2. In the dark stick a drop light in the stoves to look for cracks in the cast iron panels, doors, internal plates ( 602 has 2 on the sides and smoke "deflector" above), and especially the joints all around. Messy, but finger in stove cement into all joints.
3. Be sure the mechanical operate: doors, internal damper, thermostatic air control (Defiant).
4. You can get a smoke pellet from a dealer to check air tightness. Do it it with your windows open !
Remember that those stoves were a good but older pre-EPA technology. The post EPA (1989) stoves, catalytic and non-cat, not only burn cleaner WHEN BURNT CORRECTLY, but burn much more efficiently. When we changed over in the early 90's to EPA stoves, we cut our cord use by at least 1/3. Not shabby. Our Jotul 602 was in the sauna until sold just last year.
Good stove brands: Woodstock, Hearthstone, Morso, Jotul, Pacific Energy. The "Vermont Castings" branded stoves (CFM/Majestic)do have quality problems according to users, and warranty and repair difficulties.
Look at your lifestyle, what you need to heat, and aesthetics (e.g. looks, color, loading).