![Impulse Dog](http://farmtractorrepair.com/cdn/shop/products/GR1266-2_{width}x.jpg?v=1569310862)
Impulse dog for Fairbanks-Morse FM J series magnetos with a two-piece cap found on many Allis-Chalmers tractors. This dog will only fit couplings that have been updated (will not fit onto original style couplings). Replaces Fairbanks Morse part number D2565.