I thought it was a strange choice to give Hoist a cutaway roof, but it's screen-accurate - in the opening scene of Hoist Goes Hollywood and in one overhead shot of The Master Builders, Hoist was drawn with the cutaway roof.

After watching transformation videos of both Hoist and Trailbreaker, the term 'remould' or 'retool' doesn't seem appropriate and undersells how different Hoist is from Trailbreaker, even with 'very heavy' attached. At the risk of being pedantic, 'new mould with shared parts' seems more appropriate, since the two figures have very little common engineering. Without having both figures in hand, it seems like the only shared parts are the front of the truck, the wheels, and the doors. Are there any other common parts?