Well done finding that gearbox casing. I think I spotted it for sale and was sorely tempted myself. I'm glad I didn't bid on it, as it went to such a good home. If it is indeed the box I saw for sale, its a 2006 gearbox. Does it have a parts number with prefix 080-B01-????
If you would find it useful, I can PM you a list of Honda F1 parts numbers and how to interpret them. The 2007 gearbox cost Honda £105k for the casing alone, and I'm sure the '06 casing must have been around that as well. Brilliant find, and quite a bargain!
Looks quite similar to the '07 box: http://www.flickr.com/photos/fan6s/5927 ... 047935753/