[R-390] R-390 CR-801 replacement

[Ken]

Good morning gents,

While we are on the subject of the R-390...
I would like to replace the Selenium rectifier CR-801 under the power transformer with a modern bridge rectifier. 
The problem I am having is I can’t find a suitable device that is small enough to fit ‘and’ has a mounting hole.  Everything I have come across so far have small plastic cases with no mounting hole. 

Does anyone have a suitable part number I can search for? I would be very grateful. 

Best regards 
Ken