[PAradiogeek]

Kirk,

I don't know how to sort this bad boy out. Looking at the Model 979 schematic, there are differences. On the good side, that schematic shows 2 caps (both 20 uF), but there are tube line-up differences. The converter is a 6K8 (instead of a 6A7), the IF is a 6K6 (instead of 6D6), the rectifier is a 25Z6 (instead of a 25Z5), and the ballast is a BM43B instead of a BM49C.

According to my tube substitution data, the 6K8 and 6A7 are not subs for one another. The 6K6 and the 6D6 are similar though not direct substitutes. The rectifier tubes seem to be direct replacements.
I don't believe that the ballast tube difference is very significant (maybe someone down the line swapped a '49C for the original '43B).

In any event, if you want to go with that schematic, both caps are shown as 20 uF caps, but I honestly don't think the Model 979 is the right model to use. Too many differences.