It turns out that amd isn't setting the mount option that disables
connected UDP sockets.  So, since all my NFS servers have more than
one ethernet hanging off them, but all the clients use the "real"
rather than "closest" address of the machine, it was losing.

Here's the first bit of my amd map file now, which does in fact work
mounting a 1.3.3 machine from 1 1.4-currentish one.

/defaults	opts:=rw,resvport,proto=udp,noconn;

--Michael