103Z is just a typical Z5U rated capacitor - most common version out there with a tolerance of +20% or -80%.

CT42 is not a standard rating for a capacitor. Must be a vendor's part number for a series of caps. I did a search on ebay and found the caps you were looking at - those will work fine.

If you do another spin on boards -- change the caps to multilayer style. You can get cheaper and better caps in that style. And the boards are easier to assemble with this style of cap (no lead bending).

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