I replaced my timing chain assembly and oil pump in November, so it's pretty fresh in my mind. That said, my truck is a 3/4-ton and if yours is a 1/2-ton, not everything is possibly applicable.
There isn't so much a gasket as there is a windage tray with molded gasket. The oil pick-up tube runs through the windage tray and is fastened to an extended #3 main bearing cap stud on the bottom (sump side) of the tray.
The trick is to get the new windage tray between the pan and block and slip the pickup tube bell through that windage tray opening and get that #3 stud fastener attached. But I did it alone and on my back, so it can be done at home. Either allow ample time or get a helper; just having one end of the pan supported while you shuffle things around would help.
I read that the corners of the pan where (at least) the timing cover attach to the pan/windage tray are supposed to have a sealer bead. I got a Fel-Pro windage tray and it came with a small tube of black Permatex. IDK if that's included with all trays or if a subsequent spec revision doesn't call for it. I did make a small bead all the way around the top of the tray. Good luck.