[71 c-10]

hey ya'll its been a while since i'v been on here but I got a question I cant seem to find the answer to. My girlfriends dad has a true 69 z28 camaro and her mom wants to get him some stuff to go drag racing with this summer. We trying to find what the axle seat diameter is so we can get the right c clip elimiator kit. According to summit the two diffrent sizes are 1.533 in., 1.398 in. thanks in advance for the help :-)