The best way is to measure the output shaft with a pair of calipers. I don't know the exact dimensions in my head but the 1.76 is bigger around by a small amount.I have 3 sets of 1.76 planets in the shed if you want I can measure one. Also the input shaft length as mentioned but someone could have changed that(not likely but possible) Not to mention some people don't like you pulling the shaft out of a trans you haven't bought yet...don't know why but a guy got upset at me for doing it.