Knuckle Couplers for Mantua

I have a number of Mantua HO freight cars. The cars came with horn hooks attached but two of the cars also provided knuckle couplers. These couplers consist of a centering ring, the coupler, and a slightly larger cover. I would like to obtain more of these couplers but the instructions did not mention the name of the manufacturer. Did Mantua make these couplers and can they still be purchased? I have examined Accumate, EZMate, McHenry, Lifelike Proto, and Kadee couplers and none are a match. I do know that the Kadee No. 5 will work. However, I would prefer to use the type that came from Mantua. Thanks for the help.
RTB in Newtown

According to Mantua’s 2001 catalog.“New for 2001–Knuckle Coupler. Beginning in 2001 all Mantua engines and rolling stock will feature knuckle couplers(with a metal coil spring)”.
I don’t know who bot out their parts inventory but modelexpo, standard & tranworld were principal vendors.
I see in MR that standard still is listing Mantua products.

I’m only familar with their tender. About 18-24 months ago they came out with their own knuckle coupler for their tender. I will look that up and see if it was used for their freight cars.

But Mantua is out of the train business so I don’t know where knuckles would be obtainable