I don't know your set up but on my 97 Yukon I completely took out everything related to the 5.7 that was in it. Didn't see a reason for it to be there since nothing runs through it like you said. I would think running the the wire from the vss to the pcm then from the pcm to the Speedo would do the trick. Either way the computer needs to know the speed from the vss for shifting correctly and what not.