LEGO GMC Jimmy 72. This MOC represents first generation version with hardtop on.
It uses 1×2 jumper plate (part 15573) in grille and this part is known for having different versions with different part numbers that look the same from outside. For this design we need 15573 version hollow bottom connection (you can see underside of all versions in this link), its the only version that will work here. My bricklink source file uses the correct part number, so everything should be good, but if your part does not connect (because of the middle stud on underside) it means you have the wrong part version.

MOC info:
– 6 stud wide vehicle body 
– seating for 2 minifigures
– simple to build design, no opening parts 
– total 219 parts from 68 lots, all parts will cost around $25

You will get Bricklink source file that can be used to find parts automatically on LEGO part marketplaces like
And PDF format instruction file.