The SIM card is the same size. What is important is whether it is an A8P, Sim2, Esta or other SIM.
If you are not going to flash a different image, then you don't need to know unless it crashes.
All I remember is mine was an early Sunray4 and after a year or so upgrade sims were available but quite expensive so I never upgraded.
I think it is definitely not an A8P SIM