The last American heavy tank to have ever been produced. Entering service in 1957, the M103 was a direct response to the Soviet IS-series heavy tanks, namely the T-10/IS-8 as that was (at that time) the most advanced heavy tank fielded by the Soviets. Thicker armored than the contemporary M48 Patton, and armed with a long 120mm gun that would've been more than capable of ruining a Soviet tanker's day, this tank can pretty much be described as a much larger, much heavier version of the aforementioned Patton (at least in looks anyhow). This is largely attributed to the general design philosophy of American armour development during the early half of the Cold War.

At the time of writing this, I had honestly forgotten about the T43 I posted several months back, and was just about to repeat a lot of the information I had wrote for that vehicle, as the T43 is basically just the prototype/pilot model of the serially-produced M103.
https://www.furaffinity.net/view/62572593/ <--- This specific post in question.

That being said, I don't know if I should just go ahead and just sign off here for now. Part of me wants to be more detailed about this, but isn't really sure how specifically. Maybe something to think about and come back to at a later date I suppose. In the mean time, I guess I'll just leave this an open-ended thing, as I've yet to get around to doing the cleanup I said I was going to do (procrastination raaaagh).
Enjoy this big-headed tank for now I guess. Cheers!