Kevin if the hoses are all the same size, which they should, I just took mine to advanced and they measured them up and cut me the size I wanted. Just be sure you cut in the middle of the line cause the ends are going to be flarred out due to being pushed over where they are connected. Try putting the seafoam back thru the vac lines again and look for the white smoke coming out any of the hoses, that would be a good way to track down the leak....good luck, I'm in clemson, only have a 60 and a 40, haven't done any work on an 80 but if ya need a hand send me a pm.
Chuck