Fitting A/M oil pressure gauge to 21R-C -- Where's the sensor?

[TOK079]

So I decided to pick up an aftermarket oil pressure gauge-- analogue, 'cause it was cheap -- and routed the pipe into the bay no problems -- and now I can't find the sensor for the oil pressure dummy light, nor can I find the secondary sensor position on my engine. I have a wiring diagram for my car issued by Toyota that doesn't seem to be correct.

Can anyone give me an idea of where I should be looking? I've got an '82 Celica w/5 speed and 21R-C, A/C and P/S installed. And yes, I'm happy to disable the warning light. My new gauge has one anyway.
-- Cheers,
Neal

PS; The diagram says it's tucked behind the thermostat -- There's a weird plug with an internal hex removal there, in about the spot that it says it's meant to be, alongside the "spare" sensor spot -in- the thermostat -- Maybe that's it? Any ideas?

[GA61XX]

Ok... not that i would use an oil gauge with oil line... i use electric.....

you can mod the dash to have a look a like stock dash with oil gauge...

anyway next to the oil filter there is the oil switch... & under the filtr is the 2nd port....

i've used both, & had oil gauge & light....

a mate has a RA60 with 22R running both...

cheers

[TOK079]

Much appreciated! I was kinda hoping it wasn't buried under the carburettor there but so be it -- time to go spelunking.

Cheers for the info.