Have a 2005 Ram 1500 4x4, is there a steering stabilzer kit out there for the year model, have 35x12.5x20 on it and about 70 mph it gets wobbly.

 

Theres not a whole lot you can do to smooth out a steering rack. Its not like the cross-over steering found on the bigger stuff where you can just bolt an extra damper. The wobbling usually comes from a crappy balance job.
There was a thread here somewhere about using a 2wd 2500 rack cuz apparently their a bit stonger...