The "plate" is the cut that many NY delis used for pastrami. Lots of fat, like bacon, striped with fat and lean. The brisket is probably more common these days, and for lean pastrami I use the round, nice if it's going to be served cold and sliced thin. But that good fatty plate is my favorite! We called it "kosher bacon" when we were kids. I can still get it up here in Meriden, CT., made by Kayem, but you have to ask for it at the deli, they don't have it on display. They call it "black Pastrami". I've not been able to get the plate locally, so I use brisket usually. I brine with 2 cups of salt, 1/2 cup sugar, 5 teaspoons Prague powder #1, 1/2 bottle of pickling spice and 1/4 cup of minced garlic per gallon of water. After it's cured, I dry it a bit and coat it with equal parts of ground coriander and black pepper, then smoke at 180F until the internal temp is 150F. I've been using cherry lately, and I like it right well; otherwise hickory.
Dave in CT