Re: 1976 Evinrude 15 hp 15604A

[frankr]

It’s been nearly 40 years since I’ve looked at a long shaft model, but I’m assuming you are looking at a drain hole for the isolated drive shaft chamber. Short shaft models have one also, but it is up inside the outer clamshell housing. If I am correct, you absolutely do not want to plug it, as it can cause catastrophic damage to the powerhead if not drained off.

Post a picture if you are still concerned about it.