Tach signal help

Hey guys. Can one of you guys who have installed an aftermarket tach tell me where you got the signal input? I REALLY don't want to have to get a sewing needle and a meter and go searching through the FIFTY THOUSAND wires coming out of that ECM. Surely there's a tach signal in there somewhere!?

No, I need a tach signal. Basically I need something that changes voltage as the engine rpm changes. In the SN95's you need a tach signal driver which I believe you do splice into a pair of coil wires and it converts that into a tach signal. But nobody seems to make one for a S197 so I'm guessing that that means there is a tach signal already coming out of the ECM. The stock tach has to be driven off of something. Don't tell me that nobody at Stangnet has wired up a Monster tach in their '05 up!