I run a solid mounted engine plate with the spool style factory rubber tranny mount. I have run that same setup on several other cars over the last 25 years with good luck but maybe this time is different. U-joints didn't seem overly tight but I will recheck. The yoke wouldn't be able to bottom out but it ended up hanging out about 3/4" more than I would have like it to be when the car is at rest, so maybe it slipped a little to far out and caused the problem. Wouldn't it slip out of the tranny more on decel and into the tranny on excelleration?