Hmmm... Never seen a white plastic shaft seal... But any 2" shaft seal should work(
http://www.go2marine.com/product/742...in-inches.html just make sure to measure the log(part that goes through the boat) and the shaft to make sure you get the right part.
It is obvious that your engine is not aligned(the tranny is too low) so don't just put it back together before aligning everything properly. AND the misalignment has put undue stress on strut so make sure you check you bearing there when you pull your shaft. It is an easy swap when you have the shaft out and will smooth things out vibration wise if it is too warn.
Good luck with it! Post pics if you want more feedback