Thanks for the information transman! I am in the London Ontario
I was digging around more on some parts websites, and there appears to be different part numbers for the reverse drums. I found D12556A for reverse drum, no washer under the support snap ring, and D12556B for washer under the support snap ring. I am guessing they used both styles, and I might have the D12556A version. Just not sure why I have the witness marks.
I did end up reaching out to some of the converter companies you mentioned to me in another thread. I ended up with an SMR XPL-25 for my build, so thanks for that suggestion.