Thanks for clarifying. I can't be sure without a photo of the black piece you're referring to but I wonder if it's the corner you need. If that's the case, take a look at the 95-020 and see if this matches what you're looking for.
Oh no! I'm sorry to hear that. Are you saying that the 84-016 roller that you bought doesn't have a 1-1/4" diameter wheel? Or did you mean that your old roller's wheel isn't 1-1/4" in diameter? If the wheel is 1" in diameter, take a look at the 84-091. I recommend you review the dimensions for this part to ensure it matches up with yours.
The 84-091 has a 1" diameter wheel while the 84-101 has a 1-1/4" diameter wheel and a stainless steel housing with a stainless steel tension spring.
The open circle is another old design that the manufacturers that make these rollers no longer use. The newly enclosed circle design snaps onto the door corner, rather than hooking onto it as your original roller does. The new style can be a bit trickier to install but is less likely to accidentally detach from the corner.