Interesting...
was just poking around parts lists, it seems that the CTC16 and 16x DO NOT have the same FBT :O
16= 113992 (906160-501) and 16x = 115843 (906160-502 ) or so says sams.
Not sure what the difference is
Edit--
I see it now.
VERY different,
16 has HV REC / FOCUS REC of 3a3 / 1v2 and 16x has 3ca3 / 2av2.
HV/Focus circuits are quite different.