I purchased the same roller yesterday from OA Seattle at the number posted by MTW ($25 plus shipping/handling). (a ball bearing roller would be a lot better and will retrofit if I can find one with SS bearings).
The track is another problem. I find the Delrin/UHMW strips inevitably crack around the screw holes...then the rollers start bumping and grinded and ruin the roller. I'm looking at adapting one of the extrusions in the chart below, which would allow for screws through the wider side flanges rather than through the rail track. The trick is to get the correct height at the rail and also allow for the track guides on either side of the roller to clear the base. I thought about a U shaped track with the roller running inside, but I think dirt would accumulate in the U. Also considering just a slider on the door bottom like Sabre602, but the OA setup on our 440 is a little complicated regarding side to side control. Anyway this site has some additional possible track profiles...
https://www.professionalplastics.com...les-Guides.pdf
And I think the schedule 40 T-slot insert from these folks might work OK as a bottom track in conjunction with the OA roller. The guides that drop below the roller would drop down either side of the track and keep the door centered. Might have to shave a tiny bit off either side of the "V" at the top of the track rail. (BTW this profile is available in 10' lengths). The height of the track would be .7" versus the .4" I'm using at the moment, but I saw evidence of the door bottom dragging when I took it apart at the end of the summer. So a little extra is probably a good thing (for our boat at least). As an aside I'm using sliders instead of rollers along the top track on the sundeck door of our 440. Works well.
Anyway, here's the site mentioned above..
https://8020.net/freetextsearch/sear...=t-slot+insert