I'm guessing that once a chassis builder has the patterns and the jig he can build a fabricated housing cheaper than he can buy a Strange ,Mark Williams or aerospace housing.
The only concern I could see with the fabricated housing is the number of welds that could crack and or leak. You could weld attachments to a fabricated one which you cannot or should not do with the cast housing.
In my 30 years of racing I haven't seen either fail in a dragster
