I'm not sure how accurate this method is, but...
i've been looking to purchase an 04 or 05 lately and many of the dealer sites i visit list their inventory with each VIN number. Here's some 05 v6 vin numbers:
JTEBU14R550056546 - 2005 sr5 v6 4x4
JTEBU14R658029552 - 2005 sport v6 4x4
these two are take from a dealer in arizona
just to make sure, these are from a dealer in my hometown in california:
JTEBU14R650056006 - 2005 sport v6 4x4
so it looks like so far, the U and T designation still exists. hope this helps! and hope you're getting a v8 in two weeks, cause then so can i!
jason