Try Laura GMC https://www.laurabuickgmc.com/
They are selling below MSRP. I bought a 2500 AT4 there in February. The discount has decreased by about 3,000 since then but there is still a discount.
That premium above MSRP is the dealership not GM.
New truck delivered a couple of weeks ago. Tried to order one but didn't want to wait months. Laura had this in transit (one week out). Replaced my 2005. So far couldn't be happier. Little dirty but the only pic I have.