The 369 HS and HE are identical apart from the fact that the HE (Hughes Executive) had a plusher interior. Both are left hand drive 5 seaters.
The HM is the nearest to the OH6 and came with a troop seat interior with hard points and is a right hand drive 4 seater. Reason for 4 seats is that the centre seat cannot be fitted as the pilots collective is a permanent fixture.
The HM cost more than the others due to the cost of the hard points.
The only HM I am aware of was originally Irish registered and belonged to one of the Ferranti brothers. There was a specific reason why a right hand drive aircraft was purchased but old age sadly has stolen that information. I do remember Ferrantis engineer Malcolm Ebbut telling me a tall tale about how his bosses eyesight was so poor he had a ships binnacle compass fitted just behind the centre console. Anyway the first time I ever saw the aircraft I made a beeline for the cockpit and lo and behold residing on the floor behind the console was a six inch gimbal mounted ships compass!!!!!!!!!!!!!l