[Jim Maxwell]

Bob, Sorry I missed this posting when first started. The 289 Cobras did indeed have numbers stamped into the little protruding part of the block, on the drivers side rear, just below the head. This number matched the "engine number" listed on the AC Cars tag on the footbox. I have examined several 289s with their original engines (2401, 2492, 2490, 2149 to list only the 4 that readily come to mind) and each car has the number on the tag stamped into that area. I will have to check the cars to get the exact numbers for you. The number on the engine block on 2401 is 5018. This is not the same place as in the photo by Jeff, but is on the part in your photo. I'll have my partner take a look at 2490 and 2149 and give you those numbers. I haven't noticed any particular sequence, but I wasn't really looking for one.
(The tag actually has" A 5018" listed as the engine #)
I know of several more 289s that do have their original engines, so I'll check on those numbers, too.
The 427s did not have any engine numbers listed on the Shelby American tag. I don't know why they were listed on the 289s, but they were!
Your book is wonderful, by the way.