See if there infor where it was made, check the local chamber to see if there a town historian for some infor. Like all things someone out there is collecting them
If you google Gruman vans,several step van websites will pop up.then you can check out a couple of sites and follow different links and I am sure you will find some more info.It is a good place to start.also you can try u-tube because after it plays a van video it will post several other related serches for van videos.good luck
the guage clusters appear to be late 40s early 50s ford pieces. the steering column and blinker switch appear to be 60's ford. more detailed pics would be helpful