The a3 and a35 shoes are similar in shape and design but the pins that mount them to the hub are different sized. The a3 shoes actually have tougher material than the cork a35 shoes. Once you have the shoe use some small clamps or vise grips to hold the spring in place as you slip it into the groove. Between ebay and the buy/sell you can find a clutch, or shoes. I'd recommend either replacing all three or the whole 1st clutch. Its possible one shoe being worn more/less might provide balance issues, although maybe its not enough to even matter.