Stacking module part numbers: Manufacturer Part# K0644 Dell Part# 320-5171 They go in the back bays.
We purchased 4 of the 6224's and would like to stack but can't find part numbers for the 6200 series. Also unsure if it would be the SFP ports or the back bays that we need to stack them for redundancy. Thank you in advance, Scott 
PowerConnect 6224 Stacking