For the older cobra's with the hand crank Screw I used two of these and
some minor welding of the together worked for me:

http://www.harborfreight.com/1-1-2-h...ourc e=nextag


Although the ones I found years ago were a lot cheaper IIRC $9.99 ea from
a tool place in the NW US but can't seem to find them now.

CH