I have never heard a catalytic converter squeak like metal on metal. Like the ball joint noise when turning your wheel. When I had the squeaking, squealing ball joint, it would make noise when turning the wheel right to left and left to right, from lock to lock the whole range both directions. It also would make it's noise when going over bumps, even small ones on the road. When turning the wheels the ball rotates in the joint. When the wheel travels up and down (even minor movement) the ball moves from a straight up position to an angle either inboard or outboard direction. This too created a squeak, I was able to repeat that sound by "bouncing" the front end making the shocks travel up and down. Pressing on the bumper, just rocking the truck body up and down. I think the actual noise is from the vibrations on the control arm which houses the ball joint and that kinda masked the source of the noise. To me anyway. The best thing is to have someone check where the noise is while turning the wheel. In my situation the noise was clear even when stationary, turning the wheel or rocking the body up and down. As for the pitman Arm. Any time you change Steering/alignment parts it is recommended to have an alignment. If there was play or slop in the joint/link to the pitman the last time it was aligned it could have been adjusted to bring it in to spec and once the part(s) are replaced the alignment could become out of spec.
Firestone offers a life time alignment for $169, on sale right now for $129. Single alignment is $69. I always suggest a lifetime if you are going to be keeping it for any significant length of time. It will pay for itself. Of course they like to sell this because a) people forget they paid for a lifetime alignment and take it somewhere else, b) they can always make the suggestion of needed or upcoming needed repairs.
I don't usually just take their word, I always verify what they say. of course, if you build a good relationship with them, they will understand who and how you are as a customer, they will (hopefully) respect you. In turn, I personally will pay a few dollars more for tires from them, if they are even more expensive depending on tire/brand/promotions. I also suggest asking to have their senior or best alignment tech do the job. Of course they say all their techs are qualified, certified, blah, blah, blah... but we all know how that goes.
Recently I just had the three stooges align my truck, after I installed ball joints and shocks. They told me I needed to install a Cam bolt kit so they could get the alignment in. I was very skeptic about it and after reviewing the situation and researching, I found it was very common. However I do not know if it truly was necessary at that time or if the tech was in competent, guess I will never know for sure. I do know it is required at times and a valid solution for vehicles which have higher mileage with worn parts, my truck does fall into that category. Anyway I installed them, took it back. had them re-align it. I was hoping a different tech was going to do it...but no my luck same young kid. It took him another almost 2 hours...again. He did get it aligned however it several specs were just with in the tolerance. Made me wonder. Now several months later, I have tire ware on the outer edge of my front right tire. grrrrrrrrrrr. Anyway, I just called and scheduled an alignment with Firestone. with there Senior tech.
OK, ok, enough ranting...
Oh, yeah, I have heard catalytic converters rattle, either the heat shield around it. I also have heard the cats make little popping noises as they cool down, when a car sits after being warmed up. It's actually the metal contracting as it cools. I knew I was going to get back on subject. yeah me... LOL