My transfer case locks into 4 wheel high and low. Hubs will not lock. I know vacuum canister is no good because the heater door stayed on defrost. I moved vacuum line for interior closer to engine and they work. Yes I put vacuum cap on open port. Was my daughters truck and I saved it from destination the scrap yard.
The frame and body are very very good couldn't see it scrapped for brakes rotors and ball joints.
1. Is there an easy work-around to get front hubs to lock?
2. Does anyone know where I can get a new vacuum canister? Searched on-line and parts stores and only found 2WD replacements.

1999 Ford Ranger XLT, 4x4, 4.0L, Manual.

 

You want to get rid of the Vacuum activated hubs, called PVH system
They can be replaced with manual hubs, AVM makes them, also sold as Mile Marker and Rugged Ridge hubs, only fit 1998-2000 Ranger only years with PVH

How-to here: https://www.therangerstation.com/tec...hub_swap.shtml

You can Lock your PVH hubs full time, how-to here: https://www.therangerstation.com/Mag.../offroad.shtml
2001 and up Ranger had full time locked hubs, so doesn't hurt anything


PVH troubleshooting here: https://www.therangerstation.com/tec...shooting.shtml
Problem is you can trace all the lines and repair and replace solenoid...............but if the hubs have lost their vacuum seal then its all to no avail
It was a bad design, which is why Ford dropped it after 2 years, it was a problem from day 1
All Ranger 4x4s have an OPEN front differential, this means if one hub is not locked then no 4WD at all, so both sides have to lock every time you need 4WD
You must have an early 1999 4.0l as most 4.0l had Live Axle by mid 1999