The rocket kid launches a model space shuttle. Side mount, external tank, strap-on SRBs and all. However, this is set in 1972. At that time, the shuttle designs had a 2-part design - a manned booster and a orbiter. The external tank/strap-ons concept didn't evolve until later.
I withdraw this one.
I've done some Shuttle research (unrelated to this board), and by 1972, the STS, in fact, at the ET/SRB design.