I was changing out my speedometer cable yesterday and while I was taking it off the transfer case I noticed a place for a hose to hook up to. I am thinking this is for a vacuum hose for the four wheel drive.

Anyway, I would like to put one back on it but not sure where to run it to. Can anybody tell me where this hose need to run and hook up to?

BTW, I have a 87 F-150 xlt w/302

 

Dude if the truck runs good then who gives a **** just leave it be.

 

That is more than likely a vent line, Ford did not use vacuum on the 150 until the body change. The vent lines go up along the frame rail to a high point and then terminate using a breather filter.