This model was made for a RPG of Ghostbusters that I was playing with some friends back in the 90s. My character was responsible for getting the transportation and much like Ray I found the "perfect" vehicle that only needed a "few" repairs, a 1948 woody wagon.
I took a base 48 woody model, added a screen correct light bar to it (thanks to a friend of mine that collects model police cars and knew the right brand) and scratch built all the little parts for the top to make it look similar to Ecto 1.
I think the rectangular base piece was off of a patriot missile platform model. I added the ladder on one side and hoses on the other. Painted it, dirtied it up a bit, and added the Ghostbusters logo and phone number decals.
And of course, an Exto 3 license tag for the state we were playing in.
It's really hard to see, but I even made some little proton packs and put them in the back.
Since I didn't have to stay screen accurate or anything, this was a fun little build and although the game was short lived, the model has been an entertaining discussion piece for quite some time.