Lonnie's comment prompts me to make one too. Years ago I had a '67 Firebird with a warm Chevy 350 and Muncie 4-speed with all the correct side mount motor mounts and correct rear crossmember and mount.
I never broke the case. Everything inside the case, but never the case. My own experience would suggest the age and maturity of the driver might have as much to do with transmission reliability as crossmembers.
