King cruise control has been used by some with good results. They are designed for heavy duty applications. They are expensive though and only available in 12volt, I believe. They are fairly pricey though.http://www.cruisecontrolking.com/
Rostra cruise controls work well also; there was a member on other board that used to sell them.http://www.rostra.com/universal-aftermarket-cruise-control-by-rostra.php
Since I already have a King unit to be installed, I plan to use it. Otherwise I'd use the Rostra unit.