Engine Speed Signal HELP!

Hi. I can't find the white wire from my 97 Harness that originally went to ECM C3-9 from the Coil for the engine speed signal. On the 5.3 computer the white wire goes to C2-10. Where on the 5.3 does the white wire connect?

Hopefully my question makes sense. It's awfully quiet around here these days.

OK I might have figured it out. I think maybe the white wire goes from the 5.3 ECU at the C2-10 to the bulkhead connector (C100) by the brake booster on the firewall in the E8 position.

It would be great though if anyone can confirm that for me.