I went to the local dealer on the weekend to look at the 5th gens, they were having a sale new mid spec (by the way our maxima's are actually i30's with maxima trim) going for $34,000AUS which is roughly half in american dollars, I took one for a drive and was pretty impressed, and then i asked the question "Can I get one in a manual ?" The answer was no, can't special order one nothing he told me i could take the 5spd out of my 4th gen and stick it into it,($$$$) and that it would void my warranty, I even suggested i'd wait a few months for it to come over from japan, so they called nissan head office in Melbourne to find out and the reps confirmed what the dealer said "NO" !!!
This sucks so I'm still looking into whether a VQ30DET will fit thet're cheap here complete with loom and computer for $3000AUS if this doesn't work out, on goes the s/charger.

 

You can't get an I30 in the US with a 5-spd. So if your "Maxima's" are really I30's dressed down in Maxima trim then that probably explains it...

I'm an Accord guy, but the Max guys here should be able to fill you in on possible swaps and stuff

 

some 4gen I30s have 5-speeds.