I have a buddy of mine who has 1 or 2 Flat tops off of a waggy D44. What is the difference between this and the GM Flat tops? I'm currently running a converted 10b and I'm looking to do the crossover. Also, seen some posts where people are saying that I would need to get both knuckles so that my TRE's will go in, in the correct position. (bottom or top mount) What exactly were they talking about, I only want to do this once until I get my D60. Thanks for the info as always.