I was able to fit a pin in my old Ford Escort panelvan
an upright Space Invaders though stuck out, so we had to tie the doors closed 

I also used to carry a few pins in the Escort van i used to own. Actually the first three pins i bought 20 odd years ago (Stern Stingray, Gtb Abracadabra and Bally 6million$man) i transported with the backboxes still attached and tied the doors closed! it wasnt til years later i discovered the backboxes could be unplugged and removed