'83 FC Won't Start...

[imgetnab2]

I'm still trying to find the culprit to my bus not starting. When I
turn it over, the engine briefly turns slowly, and then I get
the "da-da-da-da-da-da" of what sounds like dead batteries. I had
the batteries load tested, and they all failed, so I purchased 4 new
ones, and also replaced the battery cables in the battery
compartment. After replacement, I still get the same "weak battery"
response from the engine. I am measuring 12.55 volts at the starter,
and even when charging the batteries with the generator, I can't get
any different reaction from the engine...

Am I missing something obvious that I need to check? I've also
checked the cable connections back by the door, and they seem to be
good. Are there other cable junctions that I may have missed, or
particular areas I should check?

Any sharing of experience with this would be greatly appreciated!!!
This is really getting frustrating.

Thanks much!

Ken Johnson
'83 FC 33
Midland, MI