TOPIC: 1972 MerCruiser 165 Trim Gauge

I am going to be fixing up an old 1972 Cruisers Inc Bonanza this summer.
I am beginning to collect parts, currently looking at replacing the gauges.
I got a set of Faira replacement gauges, which does not have a trim gauge. I think I remember reading somewhere that they changed over the years.
Can anyone tell me what kind of gauge I need as many that I have seen do not look the same. Do I need to change the trim censor?
I would greatly appreciate any direction or suggestion as I am feeling a little lost on this issue. I would like to get the gauge soon as I want to make dash panels soon.

It's a MerCruiser 165 (not sure which, as there is no serial number, but it is pre-Alpha)

Actually, a trim gauge is pretty useless. When you work the trim, you can feel where it needs to be just by the way the boat rides. Assigning a value/number to wherever the trim is set is pointless. More people, more gear, etc. will require trim adjustment. Believe me, when you reach the "sweet spot," you'll know it.

As far as I know, all trim gauges are calibrated the same except for OMC which operate opposite.
Trim sending unit will work with newer gauge.

I agree, trim by seat of the pants feel BUT the gauge can be helpful in shallow water applications to give you an idea of drive height.
And BTW, the senders are driven by a hydraulic "slave" cylinder that sometimes got out of whack giving a false indication. Tilting drive full up & full down once will reposition the slave cylinder to where it should be by way of an internal bypass valve.

If it's a '72, then the trim limit switch is at 12:00 position and long since inop, requiring you to push 2 buttons to get the drive up at all. So you loose the action of the trim limit function which at least gave you an idea it was up 15 degrees minimum.

Thanks guys.