Contact TPI again, but ask for the J-105 plastic extrusion. It is the same as J-30 but about 3 inches longer. With shipping it is about $50 to your door.

Here is email quote from TPI's Isa Sanchez "We can send you two hatch slide extrusions (#32009)that we use on the J105s; I am not sure what was used on the J30s but you seem to believe it is the same part."