I don't know about the interchangeability between Camaro's and pickups for the ball joints. Another possibility is that they used 73-87 pickup control arms, spindles, etc. if the bushings are rubber. That is another easy conversion. It uses the crossmember and all out of the later model pickup. I am just guessing that with the 5 on 5 pattern, it is most likely not Camaro.

The ball joints are usually riveted to the upper control arm and pressed in the lower arm. Replacement upper ball joints are usually bolted in.

It sounds like you might be spending a little time figuring what parts the previous owner used to make the conversion.

Good luck.