The very earliest Carreras had non-T on the dials, and were also characterized by long and thin hour markers much like on yours. It’s probably worth checking the serial number of the case to see if it makes sense for a non-T dial. Here’s my early 3647T for reference.
Edit to add: I forgot to mention there are several other clues as to whether it’s an early version, such as how the movement bridge is signed and what type of caseback is used. There’s a good reference guide written on Hodinkee (from the early days)…
https://www.hodinkee.com/articles/understanding-the-earliest-heuer-carreras