but most GM vehicles had a transmission crossmember that bolted to the frame.
I know when trucks moved to an open driveline in the mid 50s, this crossmember wasn't used. The transmission cantilevered behind the bellhousing. I'm not sure when it changed again to a support on the tailhousing, but there was a time when that crossmember was not being used.
It might be a good idea to put the crossmember in to support the tail of the transmission. Your motor being stronger than stock can cause some issues.
