Installed a Henntec for a T-72/T-90 that will be mated to some HL metal T-72 idlers. I have some, but the bearing is 5mm and the Henntec shafts are 4mm. I have ordered some 4mm bearings that fit the idlers. Also I poured resin in the bottom of the hull which really stiffened it up. I learned from my first time doing this to seal up every hole with hot glue before pouring the resin. Didn't lose a single drop this time.