My VW camper has an automatic transmission with the rear support in
the form of a 4" x 1" rubber lined slot. Into this fits a flat metal
plate which bolts to the chassis.

The rubber is worn and the metal plate is a very sloppy fit, and I
haven't been able to find a replacement.

Does anybody know how you'd get this refurbished or is there a DIY
solution? Frost have a hard rubber moulding kit, but I don't know if
this is up to the job.