does anybody know - when a panther fired, did it rock on its suspension thru recoil, if so, can this be modeled?

There was some that I have seen in videos, but momentary and not too pronounced. If the kit has separately molded suspension arms, then it can be replicated.
Just imagininge the physics. there is going to be a greater amount of rearward motion than downward, as the projectile is being forced in the opposite direction. I would think the greatest amount of movement would occur when the cannon was in full recoil. So that's another thing you'll have to do; model the cannon barrel in full recoil.
Seems a lot of work, but I bet you could pull it off nicely.

ok got that hehe
so most of the action would be on the rear suspension right? as for the barrel - that would recoil back into the turret wouldnt it? so if thats the case, do i model it shorter, as if its doing that?

cheers alpha

Too add to what Bob said, I think the backward motion would be translated into a lifting of the suspension in the front but not much compression in the rear. And keep in mind this is if the gun if fired straight forward. If you model it shooting sideways then it the force would be translated to a lifting of one side.

Rob