Awesome video, got new struts to replace my coilovers in my 06 GTO (they suck) and now I feel confident in assembling the new KYB struts with the Pedder's springs! I think I may need to replace the upper spring seats though, the bearing surface was corroded enough to make it no longer smooth.
I have not been able to find it. The instructions that came with related parts didn't have it, and I wasn't able to find it online. The GTO forums seem to be aware of this lack of information, too.
Had to dig up an email from April 2018 to confirm that this part number is what I purchased. PED-4358 is available here: amzn.to/2YEfrSU (Using that link helps us out if you buy from Amazon, but shop around, you may find that part number cheaper elsewhere.)