The easiest answer is that Toyota SUCKED at record keeping.
The list was Marv's from Toyota and is not an exact depiction of build dates if you look at it as "it must be correct"
Early cruisers were very sketchy as the amounts being shipped and sold were not in line and many cruiser were sold as new sometimes years past their build date. This can be seen in the earlier cruisers listed here. Some 25's were even sold like 4 years after build .... they sold off what was on the shipping lots. I had conversations with a port worker and even he said that they sat for years... never seeming to move. So trucks built/shipped/sold is somewhat sketchy in earlier years.
You may have noticed that in the mid 69 time fame the numbers jumped from begin to end starts on the vin
most vins on the list start the vins for the month.... some vins go to last for the month
Mid 69' there was toyota first major recall due to brakes and factories went through an overhaul to inspection improvements as well as factory improvements to the management/control/organization company wide and therefore this was one of those times the numbers flipped and could be a contributing factor possibly
so if you look at it as this is the start vin and this is the end vin.... you'll go crazy
could be soooo many different factors contributing to the off numbers.... however it still points to one thing .... MrT sucked at record keeping.
It's more of an approximation