The 737 is serviced from the RIGHT side. Strickly speaking, should not the GPU be on the Right Service side, ( along with the other services). ? Placing it on the Left side, has the potential to interfere with docking and undocking .. etc. Geoff Opps: Subject should have been GPU .. ( cannot edit/correct that -- maybe a MOD can please. Tnks )

I would say it depends on the ground handler. Their SOPs are more indicative, regardless of service side. To be honest, most places just use the jetbridge connection, where available, which would stem from the side of the Main Cabin Door. Pre-Conditioned Air also comes off the bridge at many locations.