Can't find replacement transom seal for 1979 OMC 800

Perhaps someone can shed some light on solving my problem. I have a 1979 OMC 185hp, 800 series stern drive. The transom seal is cracked and leaking. I bought the boat new, have had the engine and stern drive out for engine mount repairs, and have had to rebuild the lower unit twice and replaced the water pump once. I did all the work myself. I can't find a replacement seal that matches the old seal both in size and hole pattern. The parts schematic for the intermediate unit calls for replacement part #909572, (http://www.marineengine.com/parts/o...tern+Drive&section=Intermediate+Housing+Group). The transom seal plate #911872 in the schematic shows the correct hole displacement, but the seal #909572 shows a different hole displacement. I noted this discrepancy in the picture on the schematic, but thought it was just a poor photo and ordered the part. When it arrived, it was just as pictured and not the same as the old seal on the boat. I found another source for the part (https://www.boatpartheadquarters.com/SearchResults.asp?Search=GLM-86710&Submit=Submit) with a cross reference to GLM-86710 and its' picture had the correct hole pattern; however after ordering it, it was wrong also. At this point I don't know what to do. I contacted the folks at marineengine.com, but the were also stumped, and couldn't answer the problem. Can anybody help me out with this dilemma?