Need help identifying electrical part. 94 sunsport

[PoPz]

Ok so i'm going on a trip next weekend to Millerton and was geting boat ready and trying to chase down battery warning buzzer gremlin, which i think i fixed by redoing/clean the ignition connections and sealed with liquid electrical tape, I also was trying to figure out why my rpm gauge is flittering around sometimes but mostly is pegged in a position between 1k and 7k. However the motor and everything is running fine, all connections to gauge are tight, so i'm ordering a new gauge, but won't be able to change before the trip. I was tinkering around on the engine checking the electrical connections all around, and near the circuit breaker and starter relay there's a porcelain rectangle with wires going to the PCM cycloid and to the starter relay. Well i found part of that porcelain rectangle sitting on my transmission, so clearly it's broken and i have taken it off to take the marine mechanic tomorrow. Hopefully he has it in stock, other wise i'll have to put this one back on.

So my questions are:
What is this thing?
If i have to use the broken one can i use electrical tape to keep it together for the weekend?
Would this possibly be a cause of my tach gauge going coo coo?

I have posted pics of what i'm talking about

1994 Supra Sunsport
PCM 351 Windsor motor

[agetech]

That part is the resistor for the ignition. Looks like part of the porcelain shell just broke off. Don't worry about it, if the boat starts, it is good. The boat will not start if that resistor is burnt out. Don't tape it, it gets hot when engine is running. The resistor is not needed if you convert to electronic ignition.

[PoPz]

That part is the resistor for the ignition. Looks like part of the porcelain shell just broke off. Don't worry about it, if the boat starts, it is good. The boat will not start if that resistor is burnt out. Don't tape it, it gets hot when engine is running. The resistor is not needed if you convert to electronic ignition.

What does the electronic ignition in tale? Does it have anything to do with points on distributor? Or is it just changing the ignition on the dash? I was talking to my mechanic and he was saying that i should check if there are points on the distributor and if it has them i can bypass the resister all together. Or maybe he said if it doesn't have points...

I got the part, the boat shop called it a ballast resister, pcm 351 manual called it ignition resister like u did, installed it and all works well... My RPM gauge even worked for a min, but then it locked in a position between 1k and 7k again... so i'm at a loss with that one, but i'll work over the winter to figure it out.

[agetech]

Yes, the electronic ignition will replace the points and do away with the resistor, you can get the kit from Ski-Dim or you can get a Pertronix from a parts house like Jegs or Summit. Make sure the kit you get is for marine use.
The feed for the Tach comes from the negative side of the coil, check that wire, sounds like an intermittent short in the Tach.