1974 Classic information request

['TIL MONDAY]

I recently purchased a 1974 Newel at an auction in Madera, CA. I’ve always wanted a diesel pusher but, never thought I would be able to afford a Newell. Well I saw this older one and I wanted to make sure it wouldn’t go to cheap (unless it was to me).
It runs. I drove it home. It needs some updating on the inside and the frig needs to be replaced. Other than the frig and freezer everything seems to work. I met the previous owner and he says it’s safe to go anywhere.

The engine is a cat 1160. As I research it seems that an 1160 is a version of a 3208? Is this correct? I would be interested in hearing your experiences with this engine.

Also, I need to replace the rear window. The glass is cracked and about to fall out. Can I just take the frame out and have the glass replaced?

Is there anyway to get an owners manual from 1974?

Responses to any or all of my questions will be greatly appreciated.