HRO-50 questions

[N5AIT Allan Stephens]

Gang,

     The HRO-50 I recently got at an estate sale (with A thru F coils)
is now working.  Not yet in the operating position, but that should
happen ere the week is out.

     QUESTIONS:  I find reference to two models: the HRO-50 and the
HRO-50-1.  (1) What is the difference between the two, (2) can the
one be modified into the other (50 to 50-1), and (3) is it worth
the effort?

     Also: as far as I understand one can use coils from earlier
HRO-s and they work, but the HRO-60 coils will NOT work in the
HRO-50.  True?

     And I am looking for an AC coil for the critter, and the
National XCU (?) xtal calibrator that plugs in in the inside.
Any help?

      And as always... thanks a lot!  I DO plan to put it on the
air for CX  >>>>WHICH IS COMING UP THE LAST SUNDAY THIS MONTH<<<
  (shameless plug)

     73,  Al  N5AIT
  ...and info on "CX" - the Classic Radio Exchange - is in the latest
(SEP) QST in case you missed the announcements I put out here.