O-ring for distributor cap
 

Can anybody tell me if a generation 1 117 engine should have an o-ring between the distributor cap and the distributor. I have never seen one but I have seen them on the generation 2 117 engines. The reason I ask is 2 times I have had the engine die after going through high water (2 or 3 inches deep). Today, I tried spraying water on the engine, plug wires and plugs and the engine continued to run fine. While I was there I decided to spray some cleaner on the front of the engine which was dirty. Engine still running. When I sprayed the front of the engine to wash the cleaner off the engine quit and would not restart. Plenty of fire from coil wire but nothing from #1 plug wire. There was water inside the distributor and water between the cap and the black covering Bosch uses on the caps. I used compress air to dry the cap and the engine started with no missing.
I checked a 560 engine I have and it had an o-ring between the cap and dist. Of course it wouldn't fit my 500 engine.

Anyone have any ideas or has anyone seen an o-ring on the older distributor caps?

Thanks

PaulM