I thought I'd recheck the Short book for some clearer reference to the sourcing of turrets.
Three types used:
Some ausf. A taken straight from the production line, mostly went to the Hitler line.
Then some earlier ausf. D, presumably from reconditioned/battle damaged/ converted stock.
And finally a specially designed turret, the 'Ostwallturm' or 'Ostbefestigung', with a narrower mantlet, cupola replaced by a simple hatch with a single periscope, & roof armour beefed up from 16mm to 65mm.

He then descends into much detail on production figures and manufacturers... c.180 turrets deployed in this way.