It may be the starter solonoid, which I think on these is mounted on the starter. Coil or contacts in these can fail without warning, usually with just a couple prior "stumble". If you locate it, and determine which (smaller) is the solonoid engage power, check it for 12vdc when key is in the start position. If not trace back or it is your immobilizer. You can also run a "hot" lead jumper from positive to the terminal on the coil to see if it 'kicks'.
Starter spins, so it is good.