Butler Bros Mark 5 logging truck

[JensR]

Crawler modellers use various foam inserts. I would assume that they are not typically as loaded as this truck, but it might just do the trick!

BTW, is this a Traxxas Diff?
Which model is it from?

[TheMachinist]

It's a Traxxas Tmaxx diff. We are going to cut the plastic housing and add a rear pinion to the front diff housing to power the rear axle. We use these diffs in my Dads Challenger log truck and they work very well.