Need Service Bulletin Modifying Cooling System 55 HP

[DougInRomeGA]

I have a 1976 55 HP Evinrude.

I have a 1976 55 HP Evinrude. I need a Service Bulleting that explains how to add the "telltale" or water indicator to the top of the block.

Please let me know If you have a good source for service bulletins for such old engines.

Thanks