[ICOM] IC-751 vs 751A

[k2cb at comcast.net]

Good afternoon, 
  
I have an Icom IC-751A that has been sitting here with an unrepairable RF Unit board.  I recently found a lead on an RF Unit board from an IC-751.  Are they interchangeable? 
  
I recall that the CPU/PLL circuitry was upgraded from the 751 to the 751A, but is the RF unit the same?  
  
Thanks. 
  
Eric 
K2CB