Re: Speedo and trim gauge question
It's possible the speedometer has a plugged tube leading up from the pitot, I'd check that before replacing the speedometer. Disconnect the tube from the back of the speedometer, if the reading drops down to 0 you had a plugged tube, if not then it's the speedometer.
As far as the trim gauge, it's more than likely a bad trim sender. They tend to fail a lot. If you can figure out what wires are coming from the trim sender (there's probably a connector somewhere) you should be able to measure the resistance and see if it varies smoothly as it goes through it's range of motion. Chances are the resistance will jump around, indicating that it's bad.
edit to add: As far as replacement gauges, they're pretty generic. Several manufacturers make gauges that should work. The only thing that's the least bit special is the trim gauge, different engine manufacturers have different resistance ranges for the senders. You just need to get a replacement gauge or sender to match the engine manufacturer. And while they may not match your existing gauges exactly, there are plenty out there which are close enough that it wouldn't be noticeable.