combination RADAR/X-note

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Hello,
 
I have in possession a very rare circulated $20 note (combination replacement/radar):
 
Birds issue, Thies/Crow AIX 1629261.  I estimate that it is in VF condition (using the Charlton guide).  

If there are any math geeks still out there, could you calculate the total quantity of $20 bill that are a  combination radar/x-notes that were produced in the Bird series?
 
I also have 2 UNC Bon/Thies $20 Birds issue radar notes.
EVK 0489840
EVL 1843481
 
Sorry I could not supply photos.  They're in a safety deposit box in another city.
I know that these UNC radar notes probably sell for $40 to $50.  What could be a possible value for a combination radar/x-note like the one above?
 
Thank you,

Great note! You don't see too many X-note radars. I'd say the fact that it's a replacement at least makes up for the circulated grade. Your note would fetch at least $50 I would think although I would not pay more than that personally unless it were Unc. There is exactly one radar note for each block of 1000 (exept for the 0000 block). I counted a grand total of 48278 X-note / radars in the bird series. But who knows how many have survived?? Here is the breakdown by prefix based on high and low numbers seen:

$2
ARX: 2319
BBX: 4829
BRX: 3579
EBX: 3999
total: 14726

$5
ENX: 6259
FNX: 8319
total: 14578

$10
ADX: 5067
ATX: 2319
total: 7386

$20
AIX: 3239
EIX: 3599
total: 6838

$50
EHX: 2718

$100
AJX: 1693

$1000
EKX: 339