I never paid much attention to Airheads until I decided to start racing WERA Vintage a couple years ago.
Now I have 2 rolling frames, 3 engines, 4 transmissions, 3 final drives........and shelves of parts I don't use.
steering damper- 70's era bikes, early ones had a friction damper, later they had a hydralic damper. On a street airhead, the damper is most effective as a devise to mask other problems, wheel out of true/balance etc.
transmission output seal- the seal itself is no big deal IF you pull the gearbox and get it on the bench. the BIG problem is removing and replacing the tapered output flange and torqueing the big nut to 160 ft lbs. This is Critical!
tranny vent- the 6mm bolt (10mm wrench) that secures the speedo drive is drilled as a tranny vent. On a streetbike, make sure the very small hole does not get plugged with crap. This vent is insufficient on a racebike, I learned that the hard way. Now I remove the entire speedo drive and machine a fitting to connect 1/2" vinyl tubing to my catchcan.
bags- I ebayed a set that came with a parts bike I bought. There are guys making a living parting out motorcycles and selling on ebay. Some airhead stuff brings top dollar, like good bags and nice body parts, Ebay is your friend. IIRC Bob's BMW sells some repro-bags (and other parts) for the restorer types.
Triple M Engineering