Re:King City Contract Flying School
In the 13 pages(!) of accident entries at aviationarchaeology.com for King City had both.
It looks like Palo Alto Airport, Inc., the contractor, was first given PT-17s and PT-21s which were replace by PT-22, then PT-13s.
I have also seen this pattern with other PT-21/PT-22 equipped CTSs even the Ryan run schools at Tucson, AZ and Hemet CA.
I know that the Army and the Navy made an agreement to standardize training types in late 1942 on Stearmans, Vultees and AT-6s/SNJs which fits the accident records for these CTSs that I have check.
All the best to you,