RE: What motor?
Believe it or not ... the stock tamiya 540 motor is the motor that best suit for general crawling. It has 27T that can give out both torque and the rpm when you need it.
But if you are going seriously into the crawling and get your TLT stretched to be 2.2" crawler machine, then the best motor is [link=http://integy.automated-shops.com/cgi-bin/webc.cgi/st_prod.html?p_prodid=561&p_catid=26&sid=4wSJJh1Ez0Ec8tv-36105362314.c7]the 55T LATHE motor[/link]. Use the search botton at the bottom of the page and you will find lots of info about the lathe motor.