torchred,
There DEFINITELY is a harness to be considered when replacing the opticrap. The harness in question carries the ECM and opticrap signals to and from those devices. When your water pump fails it is quite easy for water to enter the optispark. Typically that is between 2 different circumferential seals that separate the 3 sections of the optcrap. If water or moisture does enter it travels everywhere within the opti. One area of infiltration, once it gets inside, is up to the bottom side of that harness that you see running into the white plastic harness receiver at the 10:00 position on the rear of the opti. Unfortunately corrosion builds up on the opti pins and female connectors on the harness. In both of my cases (yes, I've replaced 2 opti's in my first 20,000 miles on my '95!) those harness connectors were corroded. The first time the dealer replaced the opti he failed to replace the harness, even though he claimed it was corroded. Guess what, my '95 ran flawlessly for about 1,000 miles and then started to fart and poop again. The dealer then replaced the harness that I thought had been replaced the first time ($125 for that crappy little $10 harness; labor included.... 3 min. installation time). That mess cost me about $900, towing charge included. Well, due to a leaky water pump that they said was not the culprit, the second opti failed in the next 4 months. Guess what....same corrosion inside the new opti and yes, another corroded harness! This time I replace the water pump ($129 lifetime guar.), Opti (from gmparts direct for $277) and tool a needle and some carb spray to the corroded harness (could have done that myself the first time and saved that $125). I believe I have finally fixed the beast. Oh, almost forgot.... when the dealer replaced either opti #1 or #2 they crimped the fresh air vacuum hose running from the front of the manifold. I believe this made the leaking water pump problem worse because that fresh air line is absolutely necessary to help purge moisture from the opti.
PS - As additional insurance I would ask the mechanic to show you the bottom of your existing water pump before he puts that baby back on. The water pump must be removed to replace the opti. I will bet that it IS leaking, either from the weep hole or the drive bearing; probably both.
Hope this helps. I'm still mad as hell!!!!!!!!!!!!!!