The first block of docs are from Russ Jensen (http://www.ipdb.org/archive/russjensen/).

There's also a ton of info on Danny Leach's bingo site

Russ is a pinball historian, and has done considerable research using everything from personal interviews to amusement industry newpapers.

The information has been formatted for the web, and pictures have been added to present the material in a fashion closer to it's originally published form. Text in italics was added by me in a couple spots just to map Russ's terminology to what I use on this site.

The rest of this stuff is from me:

  • United Caravan overhaul has some general information about the differences between Bally and United games. However, late model United's like Caravan were not as different as the early games were