I have read about people still having heat issues with aluminum housings including vanquish. Someone pointed me to DLUX Fab, they sell truck parts but they also have a few rc crawler parts. They modified a plastic housing to use a 5x13 bearing for the inner pinion bearing. For $20 this might be worth a shot.
Info from their site
http://www.dluxfab.com/products click on store tab then rc crawler parts
"Axial Wraith housings that have had the bearing area modified for a 5x13 bearing. The bearings are set in the housing so a standard (new) ring and pinion will be just a hair too tight but perfect when broken in. Comes with gear side bearing installed."