I think you are thinking of the 155 and yes that is from the 03 era. It is super narrow at ~180mm because I used to run one on my 03-F. I don't recall actually seeing the 156 body and it looks from the Tamiya web site like it came with the discontinued FF-02.
http://www.tamiyausa.com/search.php?q=alfa+156
I am a bit of an Alfa nut (my daily driver is a 3.0 Milano) and AFAIK the Alfa 156 didn't even exist back when the 03 was released.