Double entendres are fun.

I have new stock motor mounts and a new transmission mount, but the shifting in the 240sx is still ugly. I've driven many other cars on track and I have never had shifting problems like these...about 10% of the time I shift into 4th but hit reverse or 2nd instead. I've been through one transmission already due to a 3rd to reverse goof, and I don't want to destroy a motor by fully going into 2nd.
What can I do legally? Would an engine stay rod help?

Thanks,
Timooo