I have all the service manuals for the A31 - there are 5 books in total with around 1800 odd pages including a manual dedicated just to the chassis/body, all are in Japanese. Don't bother with the one from NZ as it is just an owners manual and offers very little info.
I got all mine from Yahoo Japan auctions and had Jesse Streeter buy them for me, cost over $500 for all of them, i asked Jesse to see if we could get new ones from Nissan but Nissan Japan wasn't interested in helping.
In other words start searching YJP!!