I can take some, just need to get off my butt and do it. Basically its just two spherical rod end bearings (5/16" size) one left hand thread, one right hand thread. The nuts that the threaded shaft on them screws into are welded into a piece of 1/2" tubing and then they're screwed into that. They have a jamnut to lock it in place but with the jamnuts loosened you can just tighten it by hand to the appropriate tension. If you turn it one way it lengthens, if you turn it the other way it retracts. If you want to be able to put more torque on the link when you tighten it, just drill a hole straight through the sides of the tubing big enough to put a small Allen wrench or small screwdriver through, honestly hand tight was plenty good on mine so you probably won't need to.
If I recall correctly the piece of tubing in the center only ended up as like 1 1/2 inches long or something ridiculously short like that. I actually had to cut part of the threaded rod portion of the rod end bearings off with a dremel to get them to suck in enough because of the 3 1/2" total span from the centerpoint of the lock down bolt on the top of the AC compressor to the hole I drilled in the existing bracket that the AC compresor tensioning bolt tightens to. I cut that off right up by where it bolts onto the cylinder head and then put a bolt through that with the threaded part facing forward. I also swapped out the bolt that used to thread into the compressor with a 8mmx1.25" stud because it's actually easier to work with that way and is easier on the compressor casting in terms of the load it exerts. I'm sure a picture's worth 1000 words though. Just got to get the digital camera out there and take a picture for ya.
I used the 5/16 rod end bearings because metric ones are stupid expensive, and for this application 5/16 is so close to 8mm that it fits nice anyway. (Also handy to know for buying inexpensive hardened washers for your 8mm diameter fasteners instead of metric ones)
Material cost was all of 10 bucks or so, the rod end bearings were about 3 bucks each and the only reason the tubing was so expensive was because I used stainless and bought a 4 foot remnant of it since it didn't make much sense to pay a 5 dollar cutting charge at the metal store for a 1 1/2" piece of tubing.
If you MIG weld it, it's sorta tough because the wire feed tends to push the nut out of position in the tube end. If you have access to a TIG welder it would be much easier.
Also put something like the cut off pieces of the threaded section of the rod end bearings in the nuts when you weld em so you don't get spatter in the threads.
Now that I think of it the tube might have been slightly larger than 1/2 inch too. Just buy the rod end bearings first and then match up some tubing that just barely slips over the outside of the nuts.
Anyway that's the basics of it, it's actually pretty simple to make one.
