When I built mine recently, I used KW frame rails from Gary Wallace and cross members and suspension components from the AMT Freightliner. This was mainly because of the long wrecker bed. Given your subject has a single axle with a box van, you may consider using a Louisville kit with a different engine and transmission. The one that I built was from a another caster that is no longer in business and not A.I.T.M.. The one from A.I.T.M. is much better quality in my opinion.