This transmission bracket (cross member) can be used for an installation of a 6-speed transmission in a BMW E30. It should work with the Getrag 420G, ZF GS6-37DZ and ZF GS6-37BZ.
Weld all parts together and paint them.
The 6-speed transmission bracket for the E30 dimensions.
Use 4 square-headed M8X18 bolts (23711130250) to connect the bracket to the chassis.