NEVER SEEN IN ANY STAR TREK EPISODE NOR MOVIE, the T-3 is pure fiction on the part of writer Forest G. Brown and artist Dana Knutson. I give them credit for trying as hard as they could to emulate the Klingon designs available to them in 1985. At that time, the vast majority of Klingon lore and history had yet to be fleshed out. ST:TNG was still a pipe dream. The movies had produced exactly TWO Klingon vessels: The Bird Of Prey from Star Trek III, and the revamped D7 that was shown in the opening sequences of ST:TMP and Star Trek II. From these two vessels Knutson and Brown had to extrapolate an entire navy of Klingon ships.  And for those of you who think a personnel-carrying assault ship is a lame idea, I suggest you think again. Too many Trek fans get myopically obsessed with cruisers/battlecruisers, believing that such warships are the only kind of ship you need to make up a fleet. Well as any mediocre military historian can tell you, it takes all kinds of craft to make a modern sea navy. So it could/should be with a space fleet.
        The T-3 Mover (click here for original artwork) is an attempt to design a spaceborne 'landing craft' capable of hauling soldiers up to the planetary 'beaches' and disgorging them onto the surface where battle awaits. From a tactical standpoint, this is a great idea. In any real space war, taking over planets can't be done from orbit. Men with guns have to go down and do the dirty work. And you need ships to tote those men and their guns. And tanks. And APC's. etc. etc.
        Sadly, the T-3 is a wretched piece of work in terms of the game itself. Underpowered, undergunned, and slow, it's only effective when pitted against other assault ships, or the various monitors and cutters of the Federation and Romulan Empire. Pitted against larger cruisers and frigates, the T-3 is a sitting duck. Even if massed in groups, they don't add up to much.
        For the re-draw (in 2007) I elected to size everything according to the command pod, as seen on the K'tinga at the beginng of Star Trek: The Motion Picture.  Many of the old FASA Klingon ships took liberties with scale (a common problem with Starfleet designs as well) so I tried to rigorously stick to the command pod and the warp nacelles, when scoping things out.  So, the ship ends up being a lot more compact than its original graphics indicate.  Eventually I will get around to doing both a stern and a ventral view. 

          — BRT