100 amps at idle - 150 amps at cruise.
https://www.ebay.com/itm/For-1967-1988-Mercury-Cougar-Alternator-Powermaster-88479YT-1968-1969-1970-1971/392125670978?hash=item5b4c82e642&enc=AQADAAADAFjVrDbVsZ8oH%2F8PNHtt9VX4%2Fw7FZcmMuqsX8uaFEduVAyz291JO4SxwN42BIoyH1O4CIUJQ0JVYNUMyxUsu4vCRvdFpbTWvecJX4V5L0VUBkB7owLIKc9NjwZxCWfY6BqjbLjBlm1NG6fNN7FDwnQX7h%2FWv5X%2BOTZLxMYiE9UYUCajvHnzlP7abwM6mh%2FUQYig4d3w%2BbeWaUrQX978Ai6ariAcMx3lngJ2sn8QjdEXwnHfvPX8Bfa2ZMu%2BNGPRs%2Fp0sAyqX5gje1BJrwec6A8mxxooDJFILiqPeFC5TBejHwP4q%2FH6RGPoBO8y6uQd1TEm2Ez%2FmvdI99CF0WqpsLcdATjK0%2F4AJa2IJMv0Z%2BSQWYQ0jHFfw%2Bt%2FXGDCvmq8r0XpqMuczC9yzUhInpS2IXdOKRKjwEcwtUhff%2FHiAJLxVYid8t6G7xNeXsfkQlSKGFsT38SDxrtD3dKoK42Bng3w18WE5be2gZB5xJzT56p6MmnLUaQwdpR%2BujSgS4hPQLCu%2BM%2BhSktpxYSYWPX2MovYeXznN8AVN5Pq0fVHZHnaICMzRnDoPtUjt3HKZWjOABAbFGIECAQUPQ%2BTOFioFuQkHehKIhzMClgX7Fs9eM5lfj5%2B9EJKDH9Qt9efxunr2ZBq7XHJGQA6oOzR%2B4XndXgqvu%2Fsw59J%2FDm5%2BviGib%2FkIl4YzT8tfY%2Bt5Yg7F7VZpQ%2Bg7uastmJMu1lnB%2FHpsMq3A8VZojtRJfxQ6OjV4i6BPbbcJ%2B11L1iere0gY4bYvG1H00DFHt3GJX2t314zjVG%2FPuPJuxHQC8AohKXUebkBZbdll7CDQAK30Dt6i8TKHJh8fZHxYD72KiGcuFPwr%2BUz0zIbpNV8U1W0uQNgjVeRQu76gFebe1S0FO8MHEH0aPezhxQaMxKBBKsFfQhU5EEO1cMpSpF7cuTA4s8CJI9VZZ4GIkPNHh0mCmFakiLw%2B%2FoyIaoxhS%2Bkj1kurEcakW7XPK4tzzC5je%2Be%2BBVMB2ajRXPYH9W%2BvngHsaaaX7XbVpA%3D%3D&checksum=392125670978bffc4b5091a445bfa5241aae03c8f4a3