Where can I find old fusebox layout?

I need a fuse box layout for 1991 Dodge 350 13 passenger van (bus). I have looked at several internet sites and inquired with a few Dodge dealerships with no luck. Chilton has a wiring diagram but I couldn’t find the fuse box layout. Anybody know where I can find the layout? or how to figure it out?

Check at allpar.com. Or if you are real lucky you might find the factory 1991 Dodge van ETM/electrical trouble shooting manual at helminc.com

Hope this works.