87 chevy automatic transmission

[1fishinrogers]

while I was changing the fuel filter on my 87 silerado, I noticed a 3/16 hose adapter fitting on the top of the transmission with nothing hooked to it. I know the older models used vacuum to shift but not sure about 87, I don't see anything resembling a modulator valve. Is it a  vent line connection or other ? Thanks

[VileZambonie]

It's the vent. It should be directed away from the exhaust in the event that the trans overheats it could vent to the catalytic converter and catch on fire.

[1fishinrogers]

thanks, I'll fix that stat.