Lipo Questions

[Evolution]

Hi everyone!

I've recently ran my xmod truck around again and find that the 4nimh AAA batteries aren't adequate at producing the power I want for this truck. I was thinking of upgrading to Lipo batteries, and was wondering if the two rectangular ones are the only option? They seem to be hard to find and I was wondering if anyone has found an alternative? Also, any recommendations for chargers? I have an awd board with 4x 8958 FETS in the truck, would that be good for lipos?

Heres a picture of the truck and electronics