Battery tray is on this page of the store, use the drop down menu to select it. Internal dimensions are 168mm x 55mm and Mike says it is closer to the centerline and lower than the Losi Tray. Weight difference is probably insignificant.
http://www.rc-monster.com/proddetail...MFPbatterytray
For pics of the tray installed and the esc shelf, ignore the old style motor mount
http://www.rc-monster.com/forum/showthread.php?t=26801
Motor mount.
http://www.rc-monster.com/proddetail...d=RCMLosiMount