[jimcol]

I feel your pain. When I replaced the original kitchen faucet on my 2006 that retainer nut was a B to get off. Yours looks pretty clean. If you loosen the two screws on the retainer nut you might be surprised how easy that retainer nut moves. If it doesn't, and mine didn't, it becomes a two-person job. Wife held the faucet from above and I was able to get a pair of water pump pliers on it from below. Since I was trashing the old faucet, I cut the supply and sprayer line off right below the collar of the faucet just to get them out of the way. Made reaching that nut much easier. If you do that take the end of the old faucet that attaches to the pex, along with your new faucet to a hardware store. They will have the part you need to attach the supply lines to your new faucet.

Whoops, looks like RipNC was posting as I was typing! Anyway, it is not as daunting as it appears. Having some beer available while undertaking will help.