Installing Aftermarket Guages and keeping Stock guages functional

I recently purchased some Auto Meter Mechanical Oil Pressure and Water Temp guages. I plan to install them and keep the stock guages functional. Does anyone know exactly what size fittings I need to get for the stock locations to do this?
I could pull out the stock sending units for the sizing, but I need to complete this in one day so I'd rather not leave the car incapacitated. Is it possible to drill and tap the stock Oil pressure extension and ust that as a tee? Any help appreciated.

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1985 T-bird TC, 5Spd, Black (The Project)
1985 T-bird TC, 5Spd, Black (The Project II)
1986 T-bird TC, 5Spd, Black (The Show Car)
1986 T-bird TC, 5Spd, Silver (The Daily Driver)

You can T fitting for the oil pressure so you can run both gauges. I'll have to see if I can find the size. I think it's 1/4 NPT.
You won't be able to do this for the water temp as there won't be any flow past the sensor so you won't get correct readings. The only option I know of is to buy one of Dave Godrey's aluminum T-stat housings which has a boss on it that can be drilled and tapped for a 2nd sending unit.

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NATO Member. it's not a vice, it's an obsession
"The nice thing about each new day is nobody ever used it before" Barnaby Jones
88 TC X 2, 86 SVO, mods list at
http://www.turbotbird.com/showroom/pd_88tc.htm

Thanks Pete! The Godfrey T-stat is a good idea. It gives me an excuse to get more new parts!

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1985 T-bird TC, 5Spd, Black (The Project)
1985 T-bird TC, 5Spd, Black (The Project II)
1986 T-bird TC, 5Spd, Black (The Show Car)
1986 T-bird TC, 5Spd, Silver (The Daily Driver)