While the Taurus 66 (7-shot cylinder) may not be a "true" L-frame revolver, IMHO, it is clearly larger than a K-frame! When looking for a holster for my 66 (7-shot), I found that most holsters made for K-frame revolvers were too small for my 66. Part of that may be due to my desire for the trigger and guard to be covered by the holster. Holsters made for L-frame revolvers met my needs.I would say that the Taurus 66, at least the newer 7-shot version are like the S&W L-frames. I have a S&W model 686+ and the Taurus 66 7-shot versions that I have rented and shot feel very similar in weight and size to my 686+ which is a L-frame.
By the way, I found the Taurus model 66 7-shot versions to be very very accurate shooters - about equal to my S&W 686+ revolver. They are great shooters!