Found a weird but cool aircraft in shipbucket done by Guillermo23212, ALVAMA, Eswube, KimWolf.
Overall, there are two modifications done to the aircraft:
1. Redesigning the top of the fuselage to be more aerodynamic, adding the rear radome and adding a couple antennae (weakness of mine XD),
2. Adding the shuttle and shuttle struts.
My idea is that the small section still left of cabin would be used by technical staff overseeing the detachment of the shuttle, the overall reduced height of the fuselage is to reduce the weight and lower the center of gravity of the aircraft when the shuttle is loaded on top, and the rear radome would be used to track the shuttle from the aircraft as it accelerates towards orbit.