In the process of toy making, sometimes companies use existing parts to create mock-ups of proposed designs. This combinations of old parts and new designs are often looked back on as pretty interesting. The more odd a choice in parts use is, the more excited fans of a toy seem to get. When Hasbro licensed the toys to create Transformers from Takara, plans had already been underway to develop the combiner team format. The toys themselves however had not all been finalized. In these photos you can see what was used in creating the look of the Protectobots team.
Protectobot leader Hot Spot sporting Perceptor's head.
Streetwise was fitted with a head from Tracks.
First Aid appears to have the most original parts, but is still lacking a lot of his final colors.