Its in the engine wiring harness. It's a small black box about 1 inch by 3/4 inch. Has a black ground wire and 2 white wires. One white wire goes to the coil the other goes back into the harness. Label on it has the number 12088556. It hangs out of the wiring harness in the area above the coil. It has no provision for mounting. This is on a 93Z.

93Z M6 RED
B&M Shifter
egr, tbb, offroad pipe

 

I'd like to know the same thing, it looks like a relay huh, but I actually think it's a tach filter?