I got 2 of these Aluminum runners for Mitre slots from ebay last year
costed me only US$10 each (free shipment from Germany to Australia)
Spare 3 black plastic washers allow you to fit loose mitre track..
In attached picture top one is bottom with metal washers on both ends - for mitre track with t-slots.
Bottom in picture is top when on mitre track with 3 black replaceable washers to fit loose mitre track.
(sorry I don't have the link anymore since it was 1 year ago). Please search in ebay.
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