I read in another thread where there 8 or so different tumblers. The lock can be re-keyed by swapping them around so that they are flush when the key is inserted. Per the link above, they can also be ground down if you don't have the exact match. Of course, grinding would make more keys fit hte lock - perhaps some keys that you don't want to fit.

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.