Don't quote me on this since I knew about how the front arms on early 944s were interchangeable between steel and alloy of the same offset but I was not aware about the rears.
After looking into it in a rudimentary manner (that is, the very early 220 Turbos will use the same arm since they also share the early offset) it seems that all 944s with alloy rear arms use the later sealed bearings from 1985 onwards, where AFAIK the later offset cars were from 1986.
ECP and Design 911 working off an early 951 seem to agree with this.
http://www.design911.co.uk/fu/pt385_908 ... -and-Kits/
They use a sealed bearing as opposed to the 924 setup. They are not meant to be massively tricky with the right tool (Arrnworx sell this but I understand FWD bearing removal tools should also work) but the tool can be expensive, albeit cheaper than the labour. Some have apparently heated up the arm and had the bearing fall out and the same for reversal with varying degrees of success. The tool however does seem to make life alot easier without needing a press. Of course you could always go to a friendly garage with the hub to replace the bearings
.Without me sounding silly why do you wish to change the bearings on the rear? Are yours shot or are you doing it as a matter of course? IME sealed bearings do tend to last a very long time, far longer than their taper counterparts. On my dad's Mondeo Mk3, 3 of the bearings are still original and OK after 305k. A Mondeo prior to that did 380k without a bearing change! Admiteddly the one before his last one saw 2 bearings before 280k but that can was like Trigger's broom ; it had seen far too many bad hands in its time. I think only one of my cars on Taper bearings required renewal.
I wish I could say the same about the Escort! 3 of the corners have had to have their bearings renewed in 4k and 10 years! At least they were easy being taper, but still!