What type is the van body?
The short F4 van uses the same chassis as the sedan version. The F6 van however has been streched by 20cms. To get there Renault actualy streched the floorpan and extended the rear members. The F6 body would therefore NOT fit your GTL chassis. Adapting the van cargo area would be quite difficult to get right. One could perhaps rebuild it as a pick-up.
The red car is a 1972-ish Renault 4 Pick-up. Later the F6 became the platform for the Pick-up version.