There were two differential ratios used on 3000s: 3.909 for a car equipped with overdrive, and 3.545 for non-overdrive. The 3.909 had 11 pinion teeth and 43 crown wheel teeth (43/11 = 3.909, although it is stamped on the diff 11/43), which is what the numbers are that are stamped on the differential in the photo posted by Duane. The 3.545 had 11 pinion teeth and 39 crown wheel teeth (39/11 = 3.545).
When a BJ7 engine was to be mated with an overdrive gearbox, its serial number included an "R", which signified Laycock de Normanville overdrive: e.g., 29F/RU/H577. If the engine was to be mated to a non-overdrive gearbox, the "R" was omitted: 29F/U/H577.
I have no clue how Haynes came up with the engine number 10897 "with overdrive". There is no such change point specified in the BMC BJ7 and BJ8 parts manual -- either for engine, gearbox, or rear axle. Also, the "overdrive" and "non-overdrive" engine serial numbers did not fall in such a neat sequence.
As mentioned, engine serial number plates will dissolve in hot tank chemcals, but they can be removd to prevent that. Once the plate is gone, there is absolutely no way to positively identify that engine anymore.