This is a great tip about the wrench, I used it myself when pulling off my end links as well. On the first side I got the bottom off just fine, using a impact driver and a wrench as described. I also used force with the wrench causing as much pressure as I could and the nut spun right off. The top of the link was another story. I did not have a swivel socket, and there wasn't enough room to get my 1/2 impact tool in behind there so I ended up using a hex socket and just stripped the allen bolt end without even budging the nut. I ended up using an angle grinder, cutting off the fat nut, and then grinding down the "washer" side of it until I could see the circular outline of the bolt showing through all that nice shiny metal. Then used a screwdriver to pry up the washer a little bit followed by a chisel which then popped off the nut and it all fell apart nicely. This was a major PIA to do and took time!
Before I did the second side, I bought a $10 swivel socket extension for my impact driver, and kept some penetrating oil handy. The bottom spun right off like above, using a wrench like before. The top took some work, but I was able to move the nut almost to the end, constantly applying penetrating oil (kroil). At that point I could use an hex socket and open ended wrench, and the nut came right off. What a difference a $10 swivel socket made holy cow.
Thanks again for the tip!