park neutral wire

[gta87305]

I am in the middle of my 5.3 swap in my 95 GMC sierra and the 4 wire plug is need on the 95 for the prndl indicator but the pcm also seems to need it too. I sent my pcm to get vats deleted and all that good stuff and said he programmed it so only one wire is needed on the pcm for park neutral. Is it really necessary to have a park neutral signal to the pcm? I know IAC and im sure a few others rely on it. Can I leave it disconnected or am I gonna have to find where to get the signal from and splice it. I think it is the white wire on the 4 pin harness at the trans switch but unsure. Thanks