I have a 35' 2008 HR Neptune XL with 340 HP ISB engine. The trailing arms need to be fixed. I had the PO do this, and they used the source engineering parts. The PO was a real stickler for details and he even got all the oils analyzed. I paid for the RV from Premier RV in La Habra, CA and they too were sticklers for detail. I knew what I was buying.
Also, the Neptune is on a 4 air bag chassis. That bothers me; however, Source also has a ping tank, new bags, custom shocks ++ REK that is supposed to be very good too. The ride in my Neptune is good so I am not compelled to buy and install the REK yet, but will probably do so this winter. I had the coach in Houston last winter and the concrete roads and uneven bridges really beat us up. Outside the city and the whole way back home to Colorado the trip was great. I feel the Neptune is a very comfortable coach to live in too.
To be honest, I am torn between buying a larger (and substantially heavier) 8-10 air bag motorhome vs. staying with this lighter Neptune that really does work for us.
2008 HR Neptune XL
2012 Jeep Wrangler Rubicon