Allrighty, Battery unplugged,
Negative to Frame: -24V and No resistance (closed circuit) - OUCH
Positive to Frame: +13V and Infinite resistance (open)
To confirm, measuring the battery leads directly: +37V

Scrubbing the battery tops and gaps for three hours only got me from +10V to +12V on the positive posts at the contactors... That's making sure that all around the tops of the batteries there are no deposits. In some places there isn't enough of a gap between case and battery to get a tool inside, though.

So, how can 18 sealed plastic battery housings drain current to the case? I understand that's what's happening but just don't get HOW, exactly.

So,
-Can I disassemble the battery into the 18 individual cells without removing the acid, clean all the corrosion, reassemble and be good to go? Or are they often glued together in banks? It looks like it would be hard to get a handle on an individual cell to pull it out.

-Since the battery is in good condition in terms of output and capacity, it would be a shame to have to recycle it because of this, but are you guys thinking that's what needs to happen?

Thanks again!
-M