>>>...Summarising, a large number of 1967 machines were returned to the factory where the engines were rebuilt at the Redditch plant using later crankcases. Truck-loads of 1967 cases were sent to a foundry as feed stock, then of course a few months later they had to tool up to manufacture 1967 crankcases for spares stock. The entire exercise apparently cost a fortune....<<<
Haven't read the book yet.
I think you'll be simultaneously delighted and frustrated. Peter has lots of new (to me) material, but there is only so much that can fit in a book, so there isn't as much detail as I would have liked.
Unfortunately, he has suspended international shipments for the moment due to problems arising from shipment delays out of his control.
Do you mean tool up for 1968 crankcases (rather than 1967)?
I gathered it was the 1967 cases, because they'd just scrapped truckloads of them without thinking to retain some in stock. Possibly they couldn't do that because they were already stamped. The book quotes the rebuilds as using UNF/UNC cases, which I think were introduced fir 1969.
You, Rich and Kevin did most of the research here, so I'll see if I can get you and Peter in touch. He seems a really decent bloke, so may well add an addendum on the '-Y' and 'Y' machines.