OK, here's the verdict (since several have asked):
The best match I could find was a Tucsonix 2443-007-X5S0-102MLF 1000pF
feed-thru capacitor. It's nearly identical in length and width and even
has the same 1/4-28 threads as the original part.
Here's the datasheet:
http://tusonix.com/data/search/2443-007-X5S0-102M.pdf
http://tusonix.com/data/search/2443-007-X5S0-102M.pdf
It's available from Digikey as P/N 410-1039-ND:
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detailname=410-103\
9-ND
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detailname=410-10\
39-ND
While you're there, if your unit has UHF connectors installed, they
stock N type replacements:
Amphenol Connex 172118 (N Male):
http://search.digikey.com/scripts/DkSearch/dksus.dll?WT.z_header=search\
_gokeywords=%09ACX1166-ND
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detailname=ACX1166\
-ND
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detailname=ACX116\
6-ND
Amphenol Connex 172119 (N Female):
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detailname=ACX1167\
-ND
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detailname=ACX116\
7-ND
James K7ICU