[ModelA29]

An oddity - The pictures of 189 show the early type serial number pad (said to have been used on first 600 or so blocks).
I blew the photo up of Henry stamping 1 on a block in Oct 1927 and it's the later style pad that was up by the head. There are also photos of Henry, and others standing behind a model A engine - I suspect it it the 1st engine but the pictures only note taken in 1927 - the engine in those photos has the later pad. If you compare where Henry is stamping the 1 and where it is on the A1 engine in an earlier post I think you'll agree there are 2 engines with a 1 stamped on them.

I'm certain that there would have been multiple molds in use at the same time with changes ongoing. The Edison A has the later pad and the museum records reflect it was gifted to the Ford Museum by Edison's widow and the engine number was A1.