ORIGINAL: SoCal GliderGuider
Notice that the name on the above Thermic 36 is John Zaic. Could be that this design was reintroduced as a kit later thus you see the build up wings and fuse. Same with seeing the truss structed fuse for the Thermic 100 rather than the balsa block and tail boom of the earlier design.
The only similarities I see between the John Zaic/Jasco Thermic 36 design and the later Jetco kit is the name, wingspan, and the wing dihedral arrangement. In my opinion, the Jetco Thermic 36 is much prettier, with its Wolf Hirth wing plan form (wider chord flairing out beyond the dihedral break, then tapering to a sharp wing tip) and the full fuselage. I will try to post a picture of a Jetco Thermic 36 later.
The Thermic 100 had several variations during the Jasco era, but I do not have much information at hand right now. There is some information on the early Thermic 100 in the 1944 Frank Zaic "Model Glider Design" book that he published. There is even a drawing of it on the cover.
Just to confuse things a bit more, there was a Jetco Imperial 100 - a complicated V tailed glo powered monstrosity for radio control designed by Don McGovern. There was also a kit by Ace Products (of Pasadena CA) in the early 60's named the Zeus that was actually a very slightly modified full fuselage Thermic 100. There are no designer credits on the plans...
Arlen