[Milsurplus] PRC-25 and PRC-77 modules interchange?

[Dave]

Hello all,

I have a PRC-25 with 3 missing modules - A21, A24 and A25.  
Pretty sure I can get an A21. Are the PRC-77 modules A54 and 
A55 interchangeable with the A24 and A25. I have access to 
the latter modules.

Cheers
Dave
VK4KDP