93 VD Upright dissassembly

I am trying to take an upright apart. I believe there are two styles of uprights. The newer one has 6 smaller bolts that hold the upright together and the older one has one large bolt instead of the 6 smaller bolts.

Is there any trick to removing the single large bolt?

I was able to remove the 6 bolts on a newer upright but the single bolt doesn't want to let go.

Any thoughts on how to do this would be appreciated.