I picked up this bell housing for my upcoming nv4500 swap from advance adapters. The bell housing allows for the 1996 & up nv4500 to utilize 85-87 slave cylinder and clutch components. QUESTION IS: As mentioned, the bell housing is designed to be used with 85-87 clutch components. However, I have an L31r vortec engine from a 96-99 pickup that I bought new from GM about a year ago. IIRC, the 96-99 vortec 350 is internal and external balanced and uses a different style flywheel than other 86+ 350s which are externally balanced only. I know they all went 1-piece RMS in 86, but I might be making up the rest of it in my head. Long story short, is there a difference in a flywheel for a 1986 350 and a 1997 350? Just trying to figure out what to order... most accurate answer wins all my Halloween candy.