I haven't found any in any of the cars I've had, I know its an american thing (pontiac etc) to put them under the back seat, so I always thought it might to an urban myth that the Australian manufacturers did the same.

When Dad bought his Sandman (new) they gave him the production sheet along with whatever paperwork the dealers give you, invoice etc. He didn't have to go looking for it. So the fact that a lot of cars don't have it anymore may be that the original owner has just thrown it out.

In answer to Bruce's question, I know that there was a company that fitted a wagon fold down rear seat to fb panelvans (and other models probably) to take advantage of the footwells for rear passengers or to lay flat for the full load when needed. Except it required cutting out some of the side of the parcel floor (before the wheel hump) and some of the cross floor supports for the usual plywood.

Steve