FIRST OF TWO SKETCHES OF THE RS-15120. I'VE CONFIRMED THE TWO PROP SHAFTS AND THE PINION SHAFT ARE THE SAME AS WHAT'S ON THE FMC'S F140 DIFFERENTIAL. IT SHOULD BOLT ON TO AN FMC, JUST LIKE CHRIS HOAGLAND STIPULATED. EACH OF THE 3 STUB SHAFTS TAKES A 1.25"-18 FLANGE NUT, PART #1227Z936