Hummer H1 knocking Noise

[spacom]

The other week I was traveling down the road and suddenly I heard a very loud crack it sounded like a spring that broke under the drivers side, and I seemed to notice more rocking when I braked.
I took it to my workshop to investigate but only found play in the ball joints,
so I replaced all the front ball joints But still noticed more rocking than usual
and when I put in drive 2 and accelerate and let gas off I notice a soft nock like play in the transmission is this normal !
I have had every wheel off the ground and found each to have the same play
checked all shockers and drive shafts seem to be OK
what could it be.