5VZ-FE timing belt replacement interval?

This is weird:

1995.5-2000 5VZ-FE engines say you should replace the timing belt at 60,000 miles.

2001-2004 5VZ-FE engines apparently can go 90,000 miles.

Aside from the obvious: that the 2001-2004 engines reflect the inherent superiority of their owners, can anyone else explain this difference?

 

It's the documentation, not the engines ...

The original 1995.5 / 1996 scheduled maintenance guide simply carried over the 60,000 mile timing belt replacement interval previously prescribed for the infamous 3VZ V6 on PreTacos. One probable reason for this is that the 1995.5 / 1996 guide only goes up to 60,000 miles.

I have a 1997 scheduled maintenance guide that never mentions a prescribed interval for changing the timing belt - ever.

The 1998, 1999 and 2000 scheduled maintenance guides call for timing belt replacement at 90K-miles, just like the later ones.

 

Don't want to thread jack, but what if you don't hit the 90k per the maintenance schedule?
What should you do if your time over millage?
My 03 has 45k but it's 8yrs old now, what do in that case?

 

There's a point to their prescribing '90,000 miles OR 72 months' ... Unlike most other components, belts can 'deteriorate' over time regardless of how much the vehicle is driven. A lot depends on environmental conditions (heat, moisture, no contaminants getting on the belt, etc.)

Personally, I'd just keep an eye on it after 6 years (look for 'decay' in the belt itself) and wait until around 90,000 to replace it if it seems to be in good condition.