I'm sure the original poster has gone on from this question. But if any one is interested. My recent investigations into the OM Flashphoto Group lead me to a picture of the OM system from the M-1/OM-1 era that had pictures of some pre T flashes. I found info on what I think they are. One is a Olympus Flash CL which uses AG-1/B flashbulbs. The other is a PS-100G. They both were used with the Pen cameras. They are both horizontally mounted. Have found one of the Flash CL's, still looking for the PS-100G. The PS-200 and PS-200 Quick are mentioned in the OM-1 Om-2 brochure. One of the system pictures I have found includes a black horizontally mounted flash that I have not identified yet. It is interesting that with the introduction of the OM system there was not a flash photo system until the release of the Quick 300 and 310. All the other "groups" were mostly complete at the introduction.