In my HP rebuild kit I got two air horn gaskets. One marked 1250 and the other marked 2785. I cannot see any difference between them and they both seem to match the gasket that came out. What am I missing here and what should I be looking for to determine which to use? My carb number is 17066575. This is a service replacement that I bought from a Chevy dealer in about 1990 as the correct carb for my 1982 K20.