it shouldn't be going into the manifold at all it should be going into the head. so make sure you are trying to put it in the right location.
My autometer sensor fit right into the stock location. or you could use the stock sensor and splice the wires into the new gauge as an alternative.
1993 Jeep Wrangler
4.0L Tom Woods rear HD shaft
D30 w/yukon alloys, lock right, jb4x4 bracket, Rusty's HD tie rod 8.8w/ LSD,SOA xj rear 100" wheelbase, homemade greasable boomerang shackles, SS braided lines, 1" prothane body lift, 35" TrXus M/T, smitty built XRC.
lots of gen right armor and rear stinger.