I believe that all D44 straight axle ball joint outer knuckles will fit the inner Cs; Waggoneer, Chevy, Ford, IH (Scout).
Look for some travel-all or IH pickup outers at least some of them are flat tops allowing high steer.
The main differences are in the spindle bolt patterns, spindle length, wheel bearing size, stub axle diameter, spline count and length and there are some early D44s that had D30 sized ujoints.
Go to Mr. Ns page for more info;
If you have the large ujoints then pretty much any outer axle assembly will work if you don't mind a different wheel lug pattern.
If you have the D30 ujoints you will need to keep the 27 spline Jeep/Scout axle stubs, or change the axles to get the stronger large ujoint which in-turn means that you can go to the somewhat stronger larger diameter Chevy/Ford/Waggoneer/Travel-all stubs. The large diameter stubs will nor fit through the Jeepspindles or some scout spindles most are different lengths; be careful when mixing and matching. The Dana/Spicer x510 catalogues can be very handy but they are sometimes hard to find on line (try searching for x510-8.pdf).
A non unit bearing D30 outer knuckle will will fit the D44 inner Cs; (also good for changing the steering (drag-link/tie rod) height). It can be a real pain trying to get the large D44 axle ujoints through the spindle hole in a D30 outer. Unit bearing D30 parts will not fit.
5 bolt spindle mounting Ford
6 bolt spindle mounting Jeep (Dana 30 and 44), Chevy and I have seen some 6 bolt Ford spindles in the scrap yard, but they could have been mix and matched from Chevy, Ford and or Waggoneer parts).
8 bolt spindle mounting IH.
Note; that some Ford hubs & lockouts can be fitted to early Chevy spindles to change the bolt pattern to 5 on 5.5. and keep a 6 bolt spindle (See Mr. N's page).