Does anyone know of a shorter style heater fan that doesn't peak through the firewall of the 48-54 Chevy pickups?

reason i'm asking is that I smoothed my firewall and want to use the original heater.

Saw this one, but now dimensions.
http://www.classicparts.com/1947-63-1964-66-w_Air-Heater-Motor-12-Volt/productinfo/68-009/