What motor and spring thing? Do you mean the actual oil pressure sender that sends the oil pressure signal to the gauge?
In the actual instument/gauge area, where the Fuel, Temp, Speedo and Tacho are. I've been taking it apart recently doing the Indiglo needle mod, and I found that the left-part with Fuel and Temp also appears to be exactly the same as used by the TRX (And others?) with a Oil Guage - except, it's simply not there.
However I think it could be easy to put one in! All I need is to get another motor and spring thing (Which is responsible for moving the needle), and perhaps get a look at an existing TRX guage to see how to connect it up!
Yes, but i don't know what units it's in (psi, kPa, bar etc)
Well, no matter. I didn't want specifics, just knowing that it's Pressure is fine

If I can get a black face with the Oil Guage dial on it too, with dots or whatever marking the minimum, maximum and safe areas, that'd be awesome.
I'm just hoping everything else already exists within the engine and such to make the guage work! (Which I presume is true

)