Hi Tom
The 420GT has a 'none standard' table, why? It is to do with the rear cupboard arrangement which when installed uses the table rail to attach the cupboard. The transit arrangements for that table is face side down on the door side seats and the hanging down straps are meant to secure it in transit.
I used to have a 420 and it is a most frustrating arrangement. The external table bracket is a standard feature but totally obsolete in the 420, unless of course you purchase or make a suitable table that can use it.
Probably not the answer you wanted!
Clippie