If a list was made by people who own 1UZ powered vehicles and they knew the build dates of their vehicles this would probably give a good indication as to where the engine numbers fit by dates.
For example
I had a Majesta half cut
frame number UZS141-0003816
from this list build date is November - December 1991 http://jnc.farpost.com/data/framno/longindex.html
Therefore my engine number 0248144 was from Nov-Dec 1991