It's the same harness for all Toyotas 1987 and newer not including the JBL or special edition ones, I believe those are different. I'm not sure that it will fit though. It may be shaped a little different than ours. I know the 4th Gens need a special filler kit to go around the radio when you replace it with an aftermarket ones whereas ours do not. The 4th gen ones are also orange in color instead of green so they won't match.
I used to not be a big fan of aftermarket radios and their looks but it has grown on me and what you get for the money is ridiculous nowadays. I bought a kenwood unit over Christmas and was one of the first ones to get one as they were brand new then. For like $120 I got a variable color display, CD, MP3, AUX, USB, the radio data text system that shows song titles and stuff if the station broadcasts it, a two year warranty, install kit with harness and pocket, and my favorite feature of all is the bluetooth.
I've got an aftermarket radio in both of my cars now and the bluetooth is something I don't think I could give up. It's awesome. I love being able to play my music from my phone without having cables. I cant stand cables, they're my mortal enemy... The unit sounds good too on stock speakers that are 14 years old and have nearly 170k miles of use.