The manifolds have been stretched out from 38mm to 40 mm on both ends.
Fits all Airheads from 1981
Battery holder stainless steel, black coated /5 , /6, /7 or R90S ONLY for the small Gel battery or Hawker PC680
For BMW motorcycles /2 & /5 (1955-1973) and /6 & /7 (1974 -1980).