i can't speak for T-Rats..They are the current field rations for the military I believe..But I'm just an old brown-shoe soldier...MRE's were introduced after my active duty term was long over. MRE stands for Meals Ready To Eat.. They came in a heavy plastic sealed bag with various contents that vary by menu and meal. Usually there is a main-dish, a fruit packet , crackers or cookies, an accessory packet with coffee salt sugar and the aformentioned Tabasco, gum or candy of some type and toilet paper
The one I referred to had a packet of Pork in BBQ Sauce with rice, a Packet of Applesauce, 4 crackers sealed in foil, kool-aid, grape jelly and peanut butter in the individual serving packet, and the accessory pack. They served as a meal for the individual soldier with about 2000 calories if I remember correctly (one of you young guys can change that if possible)
You can buy MRE's at most camper/hiker supply houses for 4-5 bucks a meal. Just check the expiration dates when you buy. There are a lot of 'old-food packets on the market.