A friend asked me that question cause he said till this weekend he has never seen any of them without them.
He was wondering if the one he seen for sale this weekend was a rare find or just a plain Mustang with Cobra badging cause it had a solid top and he thought all Cobra II's were T-Tops
A 76 with a t-top is a quite rare car. The t-top option came out in late 76, and very few cars got them. They were more common on the 77s, but still not too abundant even on 77s. Most t-tops were 78s.