i bought my 99 blazer for 950 just needed a head gasket done. finally got it back together but there is a vacum port on the firewall for two hoses and cant figure were they go. are they for the 4wd cause it wont engage? any help would be great cause this truck is messing with my head!

 

If you have a 4-button dash switch, then yes - this is the vacuum solenoid for the 4WD actuator under the battery tray.

 

so the one goes to the actuator inder the battery were does the other go? are they two different size tubes? if so which is which? thanks