Ive had the ITR head from a 2001 head, it is stamped "R". Id be happy to show it to you but its on Lengs car he sold to some guy in NC.

Theres other ways to tell an ITR head FYI, not just casting. serial number and production date also narrow it down.

Im sure you own a ITR head if you say so, but ive seen multiple ones stamped "R" next to the casting