I don't know when this upgrade kit was released, but apparently it was long ago enough that every honest reputable retailer has it listed as "out of stock".

https://tfsource.com/c-plus-custom/thc-02b-victorion/

it's probably a long shot low chance, but just in case someone somewhere sometime knows of a reputable online retailer who still has some (or one!) in inventory, I would appreciate learning about it.

I even wanted to try contacting the company who made it directly to ask if they had any left in storage to sell me, but couldn't find their email address and website.