I've always had trouble engaging and disengaging the difflock in my 2106 CRD, so I thought I'd give the Mac solenoid mod a go. It has certainly improved it, but I still struggle to get it enagaged at times, I find I need to creep forward or backward and move it pretty sharply left and right to find the sweet spot where it all lines up and the locker enagages. From what I've read this is pretty normal with the factory locker.
Unlocking is now instant, so a great improvement there, as I used to wait ages sometimes for it to unlock.
A couple of before and after pics below, I just used 6mm poly airline and 1/8" BSP fittings that I had at work. The poly airlines I just slid down inside the existing vaccum hoses and put small sping clamps on them. I just drilled a couple of holes in what was left of the factory bracket and mounted the Mac solenoid directly to it.
The factory solenoid:
These are a great fast acting solenoid, the 532F modification to these is a waterproofing option to make it washdown proof. (Full Part# 45A-GC1-DDBA-1BA-532F)
The finished job: