I couldn't stand the flex in the panhard mount. I replaced the axle side mounts with aluminum replacements from Hot Racing and that helped immensely. Now I just have to keep an eye on the two bolts holding it to the housing as they slowly work loose. Not much, but enough that about every 10 or so hours of hard use they need a little snugging.
On the frame end I made a simple bracket out of plate steel plate that has about a 90* bend in it. Drilled two holes in it, one for the panhard bolt, an another that goes through the bottom of the chassis. This required precise placement of the second hole because there is barely room inside the chassis rail to capture 3mm nut. It took me a couple trys to get the bend and hole placement exact, but it was worth it. No more flex on the chassis mount, and the hardware stays tight. Been abusing it for over a year with a Promodeler 470 reefing on the links. Now it just wears out rod ends, and I can live with that.