If its a LHD, Just get a rust free door, cheaper, better, less hassle, easy to source etc etc, unless its a RHD nearside door, as these are like hens teeth :-[
Tbh i tried to source a good lh slider for my rhd van and they were VERY expensive , the one's i got to look at were not quite as " rust free " as the seller claimed , either that or were impaired in some other way , not saying they aren't out there just that the £500 + jobby's that i looked at had work needed .