Back plate assembly to mount 40mm Upright
Extreme

U bolt bracket to mount 40mm upright to a cross member.

Heavy duty 8mm thick galvanised backplate with M10 BZP U bolts.

Mounting area of cross member:

50mm x 30mm

40mm x 40mm

60mm x 40mm

80mmx 40mm

Also useful were two box sections have to be strongly joined at right angles.