[NLRS] Question on 10GHz feed

[W0ZQ at aol.com]

I have a Chaparral feed that came with my 26"  offset dish.  Its the 
commercial feed that was associated with the  dish.   Here is my question - can it be 
used for a 10.368 GHz feed  ?

Here is the data:
1.  It has a small round mounting flange (on  the transition end) which 
doesn't seem to fit any WR90 transitions that I  have.
2.  The window in the flange measures 0.70" x 0.49".    It is about 0.37" 
thick (deep) where it mates up with a round  waveguide.
3.  That round wave guide is about 2.2" long with a 0.750" in  diameter.
4.  The feedhorn end has four or five (depending how you  count) scalar rings 
with each scalar ring more forward than the one behind  it.    The total 
throat of the feed horn with scalar rings is  about 1.4" deep.   The entire feed 
measures about 4.25" long  end-to-end.

Will this work on 10.368 GHz ?   Is that 0.70 x  0.49 flange a problem for 
mating with standard 0.90" x 0.40" WR90 ?

73,  Jon
W0ZQ