I had a look at my spare door lock, 90-91, to by pass this feature trim
off , a la dremel, the end of the lever at the lower end of the lock. No
other features will be changed, looks quite simple as there ready access
to the back.

Perhaps the early model had the plastic cover Eric refers to.  The 90-91
lock is remove via the the door jamb.

Sincerely,

Mark Keller
91 Carat