These heater boxes offer the ability to still use your heater / defrost system and not stifle your big motors H.P. output! European made Dansk heater boxes. Large I.D. tubing along with lightweight heater box design is the key to this equation. Fits Type 1 & 2 upright engines. Custom fit application to header P/N: 3255, 3256, 7320 and 55-7320 only.