Wheel-Jack is the very first Transformer character to appear and speak in the cartoon series. He remains an important character throughout the first two seasons until his off-screen demise in The Transformers: The Movie (1986).
An Autobot in the form of a truck crane, who is referred to as Hauler, appears briefly to haul Hound up for repairs. He appears only in this episode, neither speaks nor transforms into robot mode, and is never seen again after that scene. Many fans assume that Hauler is an early version of the Autobot Grapple.
Even though the Transformer robots turned into alien vehicles on their home planet of Cybertron, they are shown having Earth-vehicle parts on their bodies. They were drawn this way on purpose, so that the kids could recognise the characters right away.
The first two human characters that appear around the 16 minute mark are modeled after storyboard artists Victor Dal Chele and David Russell.
As mentioned, an Autobot named Hauler would make his only appearance in the scene where he helps retrieve a damaged Hound without ever speaking or transforming to robot mode. A theory to this character was that originally Hasbro intended to import the original Diaclone toy; Crane Robo, in to the first wave of Transformers figures. With Hauler being the intended twelfth figure release
This however did not happen, with only eleven figures released. But by then, it was too late to recon this in the series. Eventually, Hasbro would forget about Hauler, and introduce Crane Robo as Grapple.
Hauler would eventually receive a toy release in the form of a green variant of the Grapple toy. And recover a back story that he was the green Grapple seen in the flash back sequence of Cybertron's history, in the five part season three opener Five Faces of Darkness. It was also explained that he was one two additional Constructacons that had constructed Megatron. And that he had evaded capture and reprogramming in the episode; the Secret of Omega Supreme.
Hauler would apparently take to the road to scout for any energy resources for the Autobots. Accounting for his absence.
While green variants of Grapple are released as Hauler. There has yet to be an official original release of the character.