If you have a set of these:
http://www.rccarshop.co.uk/index.php...omo-b-max.html
You will need to run a crush tube, I tried the Yokomo one but its too large
Do not try and run these hubs with out a crush tube as you'll damage the bearings and bind up the rear end
I found Durango 410 rear crush tubes are a perfect fit and you can crank up the rear wheels nice and tight with no binding
Hope this helps