It should be simple; maybe I'm overlooking the solution. I got a reproduction (Scott Drake) heater plenum and hoses for my '65. The old hoses I took off my car are square and have white ribbing on the outside. The new hoses are round and have the white ribbing on the inside. The plastic head that attaches to the dash is also different. I cannot get the plastic piece to fit from any angle. The cardboard pieces on the old hoses are broken so I cannot use those. Do I have to trim the repros or does someone have a good trick for getting them to fit?