The H-33 orbiter was designed in early 1971 to be launched atop a reusable manned flyback booster, a truly giant supersonic vehicle. The orbiter itself was similar in configuration to the Shuttle Orbiter as actually built, but it differed in that it had internal liquid oxygen tanks and expendable external hydrogen tanks, rather than a single large ET. The NASM has some good photos of a display model of the full system.
The H-33 was a popular design, at least at Grumman. A number of display models were made of it, including this detailed “cutaway” model made – seemingly – of plexiglas.
I have uploaded the full-rez images to the 2017-08 APR Extras Dropbox folder, available to all $4 and up APR Patrons. If interested, wander on by the APR Patreon and sign up. Lots of aerospace goodies available.