Are you sure you are not thinking of Rangers
Rangers have 3 slots and can either get 3 rack weapons or 2 Thompsons + a rack weapon [eg. A bazooka], as they have 3 slots and only 2 Thompsons
Cavalry riflemen can get 2 rack weapons or 2 Thompsons [2 Thompsons and only 2 slots, so no room for a rack weapon after
rack weapon = weapon from the weapons rack
Thompson SMG upgrade Their get 4 Thompsons but Relic use Little Trick
you see my picture
Slot item Add code Their put 2 Thompson Code
Dummy and MP
Dummy have set use 1 Weapon slot
and Mp set use 0 Weapon Slot
Paratrooper or Ranger Use upgrade 4x Thompson
Slot item add It be
-Dummy (1)
-mp (0)
-Dummy (1)
-mp (0)
meanwhile Their Use Only 2 weapon slot
And Have 1 slot Left For ranger