I can only find to different types of battery for that phone, the 700mAh and the 740mAH. Obviously one has a greater capacity but I wouldnt really call it extended. Are you sure such a battery exsists?
oh, I bought an extended battery for my old N73 and tbh i noticed not that great a difference.
I've been told that one exists, although I must say I'm beginning to have doubts. The phone comes with a BX40 battery as standard, and although it's OK it doesn't have a particularly long interval between charges.
Li-Ion Extended Battery for Motorola RAZR2 V8 / V9m click here
Product Description Stay connected with your family and friends by getting extra battery power today! This replacement battery has an integrated microchip that prevents overcharging and lengthens battery life. Best replacement for the original Motorola SNN5809A / SNN5810Aextended battery with comparable standby and talk time. Great bargain with excellent quality guaranteed! Type: Generic / Aftermarket Cell type: Lithium Ion Voltage: 3.7V Weight: 2 oz Color: White Extended battery door sold seperately The battery operation time depends on conditions such as: Transmitting power level Signal (distance between the phone and the base station) Network parameters defined by the operator. Compatible with: Motorola RAZR2 V8 / V9 / V9m