Chuck,
Can't find the number, sorry. Did take a few pictures and posted them here:
http://www.firstcoastcobraclub.com/g...avId=x8243addf
Look at the last three photos. The only number I could find on this starter from underneath is 551A stamped on the starter flange where the two bolts go through to the bell housing.
The dimensions - roughly - are 6-1/2" from the bell housing to the end of the starter (including the little bell-shaped protrusion on the forward end of the starter), and a little over 3" in diameter - call it 3-1/8".
Matter of fact it's small enough that when I first looked at it I thought "this little thing can't work." In fact it works better than any of the prior four starters. Just shows size does matter only not in the way I usually think!
The inside of the starter lines up vertically with the outside of the pan rail.
Hope this helps,
Tom