The unknown parent is possibly 'Jean Pierre Ferland' aka 'Mellow Yellow', given the code, the unusual tone of yellow, the petal shape, breeder, timeline, and its usage as a predominately male parent. The unknown parent is most likely a large-flowered rose given the information in 'Shockwave' that some details 'John John' are there. It would be unlikely for the male parent of 'Phyllis Diller' to be anything else. The unknown grandparent of 'John John' is probably also a large flowered type. Typically, Weeks usage of Sunsprite includes the famous R. soulieana seedling, but it seems unlikely given the information known. This makes me wonder if the unknown portion using Sunsprite is a Christensen hybrid of Sunsprite, such as 'Catherine McAuley'.

Anyway, that is my theorycraft for the John John/Shockwave/Phyllis Diller line of Weeks yellow roses.