Ralf,
A kit of this model doesn't exist, but better news is that you can make one by combining two (rather expensive) kits, the first one is a '78 or sso MPC/ertl Dodge Monster truck (kit #6344), the second is a '80 Dodge "Firefighter" stepside (kit# 1-0418, see photo).
It also came to my attention that the american resin caster
Modelhaus iis offering parts to complete the old Dodge trucks, so you might want to browse though their catalog too
My best bet is to search ebay USA, for both kits becau se the currency rate is favorable to us Europeans right now
Hope this helps
Best Regards
Luc