Securing and Aligning Ballnuts

[WandrinAndy]

I've seen and understand the recommended method for aligning BK and BF blocks... first the fixed end and then the floating end... but I've never seen a ballscrew, ballnut, or ballnut housing/support in the flesh so to speak, so please excuse my thicko questions.

The 1605/1610 ballnuts I've seen on the web seem to have a outer diameter of 28mm, and the ballnuts and ex-stock ballnut-housings/supports each have six matching bolt-holes.

Am I right in thinking that none of these bolt holes are threaded and that through-bolts are used to secure the ballnut to the housing, which allows for a very small bit of alignment adjustment?

Can custom-machined housings be made to allow for a greater degree of adjustment?

Also from what I've seen, the ex-stock ballnut housings seem to be a lot broader than many of the custom-machined housings... Is there a reason for this?