OldEastRR's comment made me get out all my Bachmann tenders and look at them closely, I have learned something. Every tender is slightly different.
I have not used the short USRA tender nor the slope back tender yet so I saw with interest that both tenders have metal rear steps and a single long slot in a metal floor.
The medium USRA tender has no rear steps and a single hole for a screw in a metal floor. I have used several of these.
The long USRA tender comes with both plastic or metal rear steps and two slots, one on each side of the coupler box. The tender with the plastic end steps also has a plastic floor.
The medium and long Vanderbilt tenders have plastic end steps and a single screw hole in the metal floor, these I have used a lot.
Several of the tenders came with a circuit board in them for connecting a decoder to (haven't used one yet, usually remove it) and all have power pickup. I like to couple my tenders close to the engine and have an assortment of Bachmann drawbars to facilitate this, but sometimes I have to make my own.