What would the collector voltage of the off transistor be in a one-shot multivibrator be?

 

Why didn't you attach your detailed schematic??

 

I don't have one

 

We are not mind readers.
You (instead of us) should look for your circuit's schematic in Google, copy it as a PNG file type then attach it to your post here.

 

There are many ways to make a one-shot.