Make sure the cap and rotor match
They are either wrong part number, packaged wrong, or just plain manufactured out of spec. NEVER in the old days did I ever worry about "matching" brands, etc on parts such as this
It looks like the United cap and their rotor work with each other only.
Use of rotor with another cap destroys it. Use of the cap with a normal rotor from one of the many company's that make rotors would place the contact of the normal rotor very far away from the contacts on the United Cap also not good. We all know how that will work out.
I will say it does look like used as a matched set would be A Ok.
And looks like Halifahops saw this same thing in another brand as well.0
Best to stick with old known good parts if at all possible.
He seems to have good stock as well as some auction sites. Worth the extra bucks for tried and true Known Old Good Parts.
Old Neihoff, Standard Motor Product's, Napa , Mopar etc,are going to dry up so stock up on at least a few.
If someone would have told you-me 40 years ago be careful buying spark plugs they are counterfeit ones out there. You woud have laughed. As time passes things are only going to get worse
