Since I didn't even get 1 reply, and no luck in finding an aftermarket muffler online which sounds like OE, I contacted Kolak. He said I have a late model 2004 4.7 since the front pipe goes straight to the Y pipe (it has 2 cats in it) with no cat in front of the muffler. He said the only way to get the OE sound w/o buying the pricey one-piece muffler/tailpipe is buy a resonator which goes in front of the new muffler. Went ahead and ordered a new SS Magnaflow resonator and muffler with free shipping. I'll have to buy a piece of 2 1/2" pipe to space them out right once received.
Also told him I hope the Y pipe never goes out since it has to cost a fortune for a new one with new cats on each side pipe. He said they sell cats where you can cut the old ones out while welding new ones right in. Nice to hear. He also told me if I ever get an o2 sensor code I best fix it real quick because it will take those cats right out or clog them. Nice to know since it has four o2 sensors on it and I'll have to keep a look out.