I had to modify my clamps to fit the smaller back of the 20, but I finally got the transom bonded in with epoxy and clamped down setting up. I normally use polyester but believe epoxy has its place and a transom replacement is one of them. I feel like I will give me a better bond to the old glass. I hate the slow dry time but once it is done I will get a few layers on the inside and tab it in then try to get the cap back on.