Multiple battery charger model questions

[Mr_Roboto]

I have a T42p model 2373-HVU and I would like to buy a multiple battery charger. According to the IBM/Lenovo site, the charge that is recommended for this model is the 22P9040 or the 22P9043 multiply battery charger II's.

Are these two my only options?

I have seen similar looking chargers, 02K6719, for sale for more reasonable prices. What are the differences?

Thank you for your help,

~Rich