I probably have a cable, but maybe not an original. It can go in a flat rate envelope for $12US, I am away from home for a few days, I will check and decide on a price.
The 131 came with a shorter coiled black cord and large DIN5 plug, but I am pretty sure that you can plug in any cable from any Model M.
I don't know where you got it or what the description is, but you called the 131 an "older model" like that made it less desirable. In my opinion, the 131 is the best Model M of all, unless you like the new ones for their lighter weight and touch. My advice is to treat this as the special one, or at least take care of the upper case shell, the square aluminum logo is way cool. The inner metal plate will be heavier, too.
Do you want a beige PS2 cable, or are you set on the black DIN?