The 4000 uses a software raid.
There are 2 different boards that I know of, 4 rev.
I've seen 4000 going on ebay for around $100 w/o drives.
Here is a link to a site that purchased some of snaps old parts. Cheaper on ebay.
http://www.northwesttechnical.com/
As far as recovery. We get asked this all the time. The problem with all raids is that they all use a different way to calculate parity. So you basicly have to install the drives in another 4000. Make sure you mark the drives and put them in the same position.
The network chip, there is no card. And it is surface mount. And it may not be that, just a guess.