Joe,

In my '80 Camper, before conversion it was a Transporter without
middle and rear seats, there were no mountings for seats or
safety belts. Just side panels had been installed because the van
was ordered to be converted.

The Z-fold mountings, which supports the rear seat/bed, are screwed
on two brackets which themself are screwed onto the firewall. This
Z-foldings are available in two versions:
 - one which fits the high of the engine bay lid. This mounting is
  commonly used by Westfalia Campers.
 - one which extends in high, about 10 cm above the engine bay lid.
  This give some additional compartment. I use this to keep warm
  clothes.

Drop me a mail I you require more information about this Z-foldings,
I may send a picture of this.

Helmut
'80 Camper