The zytanium center pin for your diff can be ordered from summit racing. I emailed power trax and they emailed me back with the part#. I forget what the number was but there's only 3 or 4 listed on summit racing. None of them indicate what diff there used on so you need to know the part number. I don't really think you need it though as I don't think you can put enough torque on the stock pin to break it, unless you have 33" tires or bigger.
EDITED: OK I guess they updated there lineup since last time I looked. Here's the link to the site. Look on the second page.
The only one they have listed for the 8.25 diff is steel, so that won't be any different than the cross pin that you already have. Probably wouldn't hurt to email Powertrax and get there opinion though.
http://store.summitracing.com/egnsearch ... 4294843254