I agree with horsesoldier.
I don't think that there would be a Leo 3. Afterall, there is only a Leo2A6.
And I don't think there is a Leo 2-140.
In the mid-90ies the Bundeswehr disbanded there tank-destroyer coys (Jaguar), because the weopon-system TOW was not better than the 120mm smoothbore.
The 120mm and its fire control system outclasses the TOW. And one round of 120mm is cheaper than a TOW missile.
Statistics say that every 1,4th shot is a first hit. So, every shot is a hit. Nice.
In my timeline we have a lot of 2A4 and a few 2A5s.