The Oversized Weapons Mount attachment has a single modification option that reads:

"All models are customized to the ship and weapon used."

That means that the ship can mount any number of oversized weapons instead of only 1?

The way I read that is that when I buy a Oversized mount that lets me add a Light Turbolaser to a YT-1300, they are fixed to model of ship and weapon type. That I can't carry that Turbolaser to a Skipray Blastboat (also sil 4) or change the weapon to a Tractor Beam without modification.

Maybe you can use modification to make the conversion from one ship/weapon to another. But maybe you can't and it's eaiser to buy a new mount.

Mmm... I think that this text:

Base Modifiers: Allows a vehicle to carry a weapon intended for a craft 1 silhouette size larger. This decreases the ship's handling by 1 and system strain threshold by 4.
Modification Options: All models are customized to the ship and weapon used.

Should have been:

Base Modifiers: Allows a vehicle to carry a weapon intended for a craft 1 silhouette size larger. This decreases the ship's handling by 1 and system strain threshold by 4. All models are customized to the ship and weapon used.
Modification Options: None.