I can't recall seeing an ex-railroad hi-rail vehicle sold 'to the public' with its rail gear still installed. The ones I saw in Shreveport a decade ago had all the mounting points for the gear installed, and still had the "railroad wheels" which put the tires over the railheads properly, but all specialized equipment -- and railroad markings -- were removed by specific intent. UPS and FedEx take special pains to ensure that vehicles painted in their colors don't get sold to the general public, and I suspect railroads are not far behind.
Keep in mind that the gearing in these things is ridiculously low -- the ones I saw had something like 5.56s, which translated into something around 50mph at redline on the 7.3 diesel in top gear. Be prepared to put the SuperSwampers on there if you expect to drive any faster!
Remember also that if the 'railroad-gauged' wheels are still on the truck, it will probably be considerably more prone to poor handling and tip-over on curves.
