[MRCA] GRC-106: RT-662 vs RT-834 Modules

[Radio Station KW1I]

I have a working RT-662 and a non-working RT-834.  I wonder what modules I 
can swap between radios for troubleshooting purposes and which ones cannot 
be swapped.  Looking from the top at all the modules installed everything 
looks identical.  On the RT-834 10kc/1kc module there is a minor marking 
difference on the module at a test point on the top and when inspected from 
the bottom has the same connector and pin arrangement, but one of the coax 
connectors is missing in both the module and the chassis connector assembly. 
So I suspect this module can't be swapped.  Are there any other modules that 
can only be used in the RT-834?

Dale KW1I