1951 ES2 primary chaincase transfer position.

I wonder if there is a settled view as to the correct location and position of the "Oil bath" transfer on the primary chaincase ? Is it positioned parallel to the ground or does it follow the leftward curve of the chaincase when located near the top ? Both variations are in evidence on ES2`s and some are even located lower down to the immediate left of the locating bolt. Factory photographs depict equally random placement so it may perhaps have fallen to the whim or mood of the fitter on the day !

Any thoughts would be of interest.