What generation is this 4251-20?

[bentheidioticnerd1]

Here is a 4251-20 that I got in a lot of 5 4251-20s for parts some years ago. Which generation is it?

[TheCarson116]

Most of it points to the supposed-2nd-generation (I’m not sure how many generations there are), but the lock confuses me as I’m not sure I’ve ever seen a 4251-20 with that kind of lock: reminds me of some 4251-20s that I have that for some reason had their locks replaced with ones from supposedly a piece of furniture of all things (or at least that’s what the key that works with them comes back to when I search the name on it).

[bentheidioticnerd1]

Here’s the inside of another one if this helps

[Caleb_Culwell (Locks and alarms)]

That’s a 2nd gen 4251

[bentheidioticnerd1]

Thanks! Any info on the lock design?