The 5-speed would be a 2002.
There are sereral places to look. Here are some boards that will get you good info
www.is300.net
www.is300forum(s).com
You can also look for stuff from Area51 TRD/L-tuned (under warranty stuff) RMM(intake exhaust suspension) HKS(intake and exhaust etc.) Toyomoto(turbo kits) and Powerhouse Racing(turbo kits).
Good luck. Let me know what you find. In a year and 1/2 I want to find a good used 5-speed and turbo it!