Anybody install a mechanical oil pressure gauge in a 66? If so, how, what type, and is it worth it? Thanks

 

I had a mechanical gage for a while...then decided electronic style was a lot better...only a wire to run and no worries about the plastic line drying out and splitting or getting a pinhole leak...

 

I briefly hooked up a mechanical gauge to verify that the stock one was working correctly in my '65 GT. After everything was a-okay, I removed it. FWIW, a mechanical gauge will require drilling a hole in the firewall so you can run the small tube up to the dash. Personally, I wouldn't bother with the gauge.