Regarding dimensions:
87041 # only has transmission rod joint (12PCS/package)
87042 # (12PCS/package) -9.5mm
87043 # (12PCS/package) -17.9mm
87044 # (12PCS/package) -22.9mm
87045 # (12PCS/package) -34.8mm
87046 # (12PCS/package) -45.6mm

1/87 Model Train Ho Scale Motor Drive Rod Connector Accessories Connecting Rod

The product is a pack of 12pcs