John, you might find it easier to find a Electrolux LXI on Ebay, scrap your old one and save the parts from it instead of finding the aftermarket wheels that mount on the runners. It's been my experience that most aftermarket parts are harder to find once it's discontinued than the OEM part is to find. Plus, with the age of your vacuum, having some spare parts around would certainly be a good thing.
BTW, in that 2nd pic of yours, that looks like a FrankenLux LX. The adjustment knob for the Automatic Control certainly doesn't look like a Original Electrolux knob would have. It appears in fact that someone had 2 LX's and combined them together.