90-91 suburban cluster swap issue

[yellowGT]

So I did the swap and thought it was all good. Then I go to start the truck and the speedo starts acting like a tach. Yes, a tach. I smash the accelerator and the speedo needle moves. This is happening with the vss wire coming from ecm to pin 18 on the cluster plug. What did I do wrong? Mind you that the white tach wire from ecm is not spliced in to anything.
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[wildwilly4x4]

is the trans in gear but driveline not installed? Positive and double checked the pin locations? I haven't wired one up myself, but I am in progress on an 8.1 swap in an '84 C10. I have swapped other trucks, but they were all cable drive speedos.

[wildwilly4x4]

Which PCM are you using?

Green/ Blue connectors show pin 50 on the green connector for electronic speedo (green/ white trace)

Red/Blue connectors pin 50 on the red connector is what should go to the speedo.