Did you try following the steps in the FSM?
http://www.nicoclub.com/FSM/G35/Sedan/2003/sc.pdf
See page 31
A/T MODELS
Removal
1. Disconnect negative battery terminal.
2. Remove engine undercover, using power tools.
3. Remove stabilizer clamps. Refer to
FSU-6, "
FRONT SUSPENSION ASSEMBLY
"
in “FRONT SUSPEN-
SION (FSU)” section.
4. Slide stabilizer downward.
5. Remove alternator, power steering pump and fan belt. Refer to
EM-15, "
Removal and Installation
"
in “ENGINE MECHANICAL
(EM)” section.
6. Disconnect alternator connector.
7. Disconnect oil pressure switch harness connector.
8. Remove B terminal nut.
9. Remove alternator upper bolt and lower bolt, using power tools.
10. Remove alternator stay bolt using power tools.
11. Remove alternator assembly to the direction of under side the
vehicle
Telcoman