That is correct. It used to be all over the place. Before Youtek era, retail and pro stock shared TGK designation. Then TGK disappeared in favor of TGT.
Today, head uses TGK for retail, TGT for Pro stock equivalent (same mold and layup) and PT (special layups and molds).
TGK and TGT are made in same factories and the difference between “equivalents” is the weight. By “equivalents” I mean the TGK344.1 and TGT344.4 for example. All TK344 molds (note the mold designator is “TK”) are identical 344.1, 344.3, 344.4. .1 is 16x19 (Barty), .3 is non-parallel drill (Zverev and Rublev)... just an example