The top air cleaner is for the 1969-1971 H1. It
has a silver finish & 3 part boot. The bottom air cleaner is 1973-1975 H1.
Notice the extra air vents & larger intake opening on top of the canister.
Intake vents were triangular for the H1D/E and rectangular for the H1F. A
snorkel was fitted to the top of the 73-75 air cleaner to cut down noise.
The 1972 H1B & 1976 KH500 are both different. Each is unique to that bike. The KH500 looked like the 73-75 unit, but did not have the extra vents on the back. It also had a silencer system that was very restrictive.
The H1B had a different shape canister & a different snorkel.
S2/A - S3/A