Lost front 4x4 a while ago and finally have a chance to figure this out. Alll lights work as normal. Front drive shaft turns when in either 4hi or 4 lo (normal). Did some troubleshooting and found out the 4x4 solenoid on the firewall wasnt letting vacuum thru it so I replaced it and it actuated the solenoid on the axle so I thought I was done. Got stuck the other day (no 4x4) so now back to troubleshooting. Put truck on jacks and pulled the vacuum lines on the axle end and when in 2 wheel drive only vacuum on one line. When put in 4hi have vacuum on both lines? Also, when put into 4hi it does not actuate but I can manually move it into position and it engages 4hi, when I flip back into 2wheel drive it does move the solenoid. thats where my problem is, why would I have vacuum on both lines? GEM module?