[Too Many Projects]

I was digging thru "stuff" on the shelves in the storage building, looking for left over '62 Impala parts to sell, and came across a loose distributor I have been looking for since I moved. It is the original distributor for my LS5 engine in the '66 Chevelle. I had a Mallory shutter wheel, electronic conversion on it for many years. Has a 526 CCW mechanical advance which I believe is still original. No clue where the vacuum advance went.
Build date seems rather early for a late January build engine ?
It's had '65 closed chamber heads on it since I bought the car in '73, so it's possible the O/O changed the distributor too.