Sorry for the confusion. I am new to the old bus world.
I originally thought the 350 was a rebuild,and maybe stock, but like 1project2many stated, the 350 was not even available when it was made, so that eliminates that.
I have heard many of these big vehicles may have come with a 6 cyl from the factory. I will be sticking with the 350 as it appears rebuilt, and they are easy to work on and get parts.
Here is the ID plate. It is on the firewall in the engine compartment.It is a GM plate. I don't know why it is showing upside down?
It may be an S as first digit, but looks way more like a complete 8 to me than an S
Thanks already everyone