I just scored a set of underdrive pulleys for my 93 GT from a craigslist ad for $25 including shipping. How can I find out which kit I have? They are black steel powder coated. They measure crank 4.625" water 5.25" alt 2.75". SUPPOSEDLY they are ASP Racing. I wonder if I can use the stock belt with this kit Also should I keep the stock alternator pulley 1.875" ?