Hi,
The 10YTaH is a 1098(1100) engine and that matches the '8' in the body Prefix(VIN) so that matches that a 1098 was fitted in the Moke when it left the factory.
The 'H' I think is High Compression, but don't get too excited, it is just high compression for a Moke.
The 10Y engine was not fitted into the Mokes and comes from a Morris 850 or Mini Van according John Sneddons book.
These numbers/letters were stamped into the Firewall, Q??B 4728 ?
Terry