It's usually on the valve cover shift plate etc on top. If someone has replaced the engine (or valve covers etc) in the last 20+ years, all bets are off!
Here's a site that will help decode your model number when you find it.
http://www.sterndrive.info/model_numbers.html
By the way, I don't want to be the bearer of bad news but if it is the "module", they are no longer available. You might find one used.
I did a quick search and found one on craigslist in the southeast that the seller claimed to be new in a sealed box for about $450.
but I wouldn't waste my time(and money) trying to keep one of those going.
Your other only really viable "fix" if you do indeed have an ECM or other EFI problem might be to switch it to a "regular" distributor and a carburetor.
AND, If it is a 1994 drive it's likely an SX (Volvo) and they are completely supportable, and are excellent drives.
My plan would be to find a complete 5.7L GM engine, flywheel housing etc (complete engine with manifolds etc) and swap it out.
Your problem may be a simple and easy fix. If you do fix it, great! (You should still be looking for a complete 5.7L bobtail engine to swap out in the future when you do have EFI/ECM problems)
just saying!