Is this what you're talking about?
I googled sandwich plate gauge and came up with a source ... However, I'd suggest Randy Rippie, Doug Rippie Motorsports ... or other performance vendor that deals in aftermarket coolers and accessory items.
Sandwich plate with gauge sensor attachment ... "sandwich plates" fit in between your oil filter and the engine block and provide an oil source for sensors ... for fitting Oil Temperature and Oil Pressure gauges.
Note: This sandwich plate does not have takeoffs for an oil cooler, it is purely for fitting gauges.
Note: I know that the C5Z06 has an oil pressure sensor that plugs in to a bolt-on housing on the inbound side of the oil filter. In my case, I replaced it with an oil cooler adaptor housing that has two -AN 10 outlets and a sensor boss to retain the OEM oil pressure sensor functionality ....
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^VIR Turn 3 '08^-MungoZ06-'03 QS/ModRed - NCCC, NASA NCM Member - Z06 Fest IV,V,VI,VII