Emil,
Back in the seventies I was an engine mechanic on these machines. I'm not absolutely sure, but as far as I remember the difference between CF5/NF5 and 'standard'
panels underneath the engine was a round panel covering the air connection. This was needed to start the starboard J85-Can15 engine. Once that was running we
started the port engine with bleed air.
cheers,
Klaas