#just now realizing that one of the ‘ken’ dolls my sister and i had as a child was a ‘dude’#but i’m certain we never had a jazzie#he must have been secondhand#that hair sculpt is unmistakable
He was possibly one of the two versions of Rocker Derek!
There were no doll sculpts created specifically for the Jazzie line. Jazzie herself used a sculpt from a non-Barbie Mattel line called Starr, as did Jazzie's friend Chelsie (Kelley and Tracy were the Starr character names, respectively.) (The Jazzie body is also extremely similar to the female bodies in the Starr line, with some simplifications.) Jazzie's friend Stacie used the early 1970s Barbie friend Steffie sculpt. Dude not only used the Derek sculpt, but also a standard Ken body.
(Incidentally, the Jazzie line was pretty much thrown together at the last minute to directly compete with Hasbro's Maxie dolls, which would explain why they were cobbled together from existing parts)
(also, yeah, once Mattel has a doll name registered to them, it is highly likely they will re-use it, which is why Stacie and Chelsie have been the names of several Mattel dolls, along with Spectra and Clawdeen. Kelley was also a re-used name.)