Is there anyone in the Navy who's job was Pact-Sn, and if so, what was it like?

They used to call this Targeted A school in my day. Basically, you go to boot camp, complete it. Wave bye bye to your buddies in your company as they ship off to A school. You stay behind at Great Lakes and go to Basic Seamanship school for a couple of weeks and then you get orders to a ship where you will do Paint chipping, painting, floor buffering , scullery scrubbing(pots and pans), mess cranking , toilet scrubbing and any other job no one else wants to do. You will most likely be in Deck Division. After 12 -18 months they allow you to strike for an open A school slot which most likely will require you to reenlist in order to take advantage of.