MAP Pick-Up on the O-320

The instructions say install the Manifold Pressure pick-up on the #3 Cylinder.
My engine is an O-320 D1A. The # 3 has what appears to be two allen head pipe plugs in the rear. One is about 10 o'clock and the other is at 8 (a cast flange seperates them). ???
Rolly

Either will work, normally the lower one is used.
Good Luck,
Mahlon