My original starter on my '06 6.0 was getting weak. Bought this new starter with great reviews and installed it, truck cranks over very fast and starts awesome. However, more times than not theres a quick grinding as soon as the truck fires and I let off the key. The starter is supposed to be a direct fit, read nothing about having to shim it or anything, just seems like the bendix isn't retracting quick enough. It didn't do this with the old starter ever, and the new one installed nicely. I know theres a million threads about this kind of stuff, but I didn't try to cram a unit on there that wasn't meant for this truck, the batterys test good, cleaned all cable ends from batteries to starter recently, but I can't figure it out, should I just add a shim and see what happens?