If you are talking about the "Texas Style" adapter that mounts a spin on directly to the back of the motor be careful here! Last weekend I blew a NAPA 1069 off the adapter.
When I got the car a Fram PH30 was installed. The PH30 crosses to a 1069 NAPA, seemed like a no brainer. Then after the 5th time I changed the oil the filter blew off, it definitely was not loose, the threads were not engaged deep enough and pulled.
After some research I found the adapter to be a 20mm X 1.5 thread which is slightly smaller than the 13/16" thread of the PH30 (1069).
The 20mm filters are:
Small Size:
STP S2903
Fram Ph3593A
Normal Size:
Fram PH3985
Wix 51626
NAPA 1626