Jon,

As this was first a conversion from single compartment to three
compartment configuration that means that the new interior bulkheads
were most likely installed in sections. These had to go into the
original tank through the openings cut for the new domes. These new
finished bulkheads may have been fabricated in a minimum of two half
round plates with flanges for riveting or maybe three plates to ease
internal construction effort. Converting these cars back to a single
compartment configuration may have simply required removal of part of
the interior bulkhead. The exterior bulkhead rivets would have
remained in place.

Just a thought on my part. I am very much open to learning more on the
construction methods of such conversions.

Bill Keene
Irvine, CA