Many of us have bought Hellwig sway bars from sdtrucksprings.com - They're a New York company but the shipment drops from Hellwig's home in Visalia CA. The S-T-P device and brackets should be available on line and perhaps through local truck shops or parts houses. If you can find it there, will be less expensive than at an RV outfit. Any shop can install these parts. So can you, simple hand tools. An OP here, ron.dittmer, can confirm whether you need to drill the chassis rails for the end links of the Helllwig rear bar. Send Ron a PM if you can't find his post about the job.
S-T-P is also an easy DIY job, but you may have to fine tune it with a couple test runs. Since it finds its own "center" it has to match the "center" of the coach's actual steering. May require a little tweaking after initial install.
I was in the SAC area a couple years ago and actually helped an OP install a Hellwig rear bar on a Chevy chassis. That one required drilling the chassis. Maybe somebody'll read this and offer to jump in. I don't think I'll be back that way anytime soon. That part of my family just moved East...
