Wiki doesn´t quote config of the measure of the tank, with or witout turret.The length of an M1A1 with gun pointed aft and locked in the travelling position is 9.03m.
The length of a Leopard 2 with L44 gun (2A4, 2A5) pointed aft and locked in the travelling position is 8.49m. Leopard 2 with L55 gun (2A6) has a travel length (gun aft) of 9.81m.
So that Spanish Leopard 2e you refer to must have its turret removed to be only 7.7m long. Is this the standard configuration of Spanish tanks? Doesn’t seem like a very practical idea to me… Cuts down on their length sure but kind of defeats the purpose.
But you say 9.81 for Leopard 2, and Wiki 9.78 for Abrams, and afaik from Lhd tanks capacity for Abrams or Leopards 2e, the Canberras were going to carry less Abrams, a few less, 6-10 less, than Spanish capacity for Leopard 2e. So prefer this source from Lhd capacity than Wiki´s or your figures to say that Abrams 2 should be bigger than Leopard 2, not 2 meters probably.
I might not matter much, but if Largs Bay has rotary platform for moving tanks i expect little difference in Challenger or Abrams don´t notice. As an example of detail engeneering thought for one or the other.
Spanish army is very complete, 500-600 heavy vehicles with turrets, Leopards, Ascods, Centauros, M60´s. Simulations system sold worlwide for the different clases, for tanks or artillery. With ground command and control and comms sold worldwide also, and also to control amphibious deployments, which Adf assessed in the past.