Vehicle Rear Suspension Question

I fully understand how the current spring animation system works for vehicles and can see a limitation it creates for something I would like to see in my game. I have seen the Bravetree solution and it is still not what I would like.

The problem is that to make a correct looking rear suspension system for a rear wheel drive car it would involve a transaxle assemby that rocks on two leaf spring assemblies with shock support. In the BraveTree car pack they left the gear box of the transaxle stationary and moved the wheel shafts as the animation. I am wondering if anyone has made a working system or animation effect that works like the real thing?