I know someone here will have the answer to this: What is the correct catalog number for the MPC $1 Series 692 note? I've seen it listed as both M87 and M95. (The note below is not in my collection; just shown for identification purposes.)
It is M-95. M-87 is the unissued 691 $1.00. FWIW, most MPC collectors do not use pick numbers when referencing their notes. They just use the series and denomination. Pick pricing is bad enough for most notes. For MPC it is horrible. Most ebay sellers who use pick numbers do not know anything about MPC. Heritage does not list MPC using any catalog referencing. The TPG's use the numbering from Schwan's MPC catalog.
Thanks for the clarification, Lettow. I've been using the Standard Catalog of US Paper Money, which lists MPCs by "KL#" (Krause-Lemke). I think they match the Pick numbers. I haven't seen the Schwan catalog, but it sounds like just listing denom and series is the best approach.