New Kato 956010 H Motor with flywheels and old style mounts. 

The specs are from the Kato website for the HM-5 motor dimensions:

This is a double shaft motor ideal for re-powering projects, and is the same type as used in HO scale KATO hood unit locomotive models

Motor dimensions: Casing length-33mm, Casing height=20.3mm, Casing Width=17mm, Shaft length=11.6mm,Shaft width=2mm