That would be the vent line.
It should cause a CEL (evap system) Like when the gas cap is off.
If its plugged elsewhere the system wouldnt KNOW it was disconnected
96BBB 28K 3.42 Bolt-ons
95BBB 100K 3.73 383 New DD...already
fixt the 4L60E twice
95 Black WB4 Hole...ee...grail
96 Black WB4 No holes in this
95BBB 189K 3.08 Old DD