Trying to import 24 fps audio

Question

I edited my project in 24 fps (not 23.98). Then I exported a 24 fps quicktime file for my sound editor and he created a mix using protools. When I import his mix (48 kHz, 24 bit wav) the computer seems to think this is a 23.98 file. When I stretch the audio it synchs fine.
Here's where it gets strange for me. If I export my stretched video and re-import it into the same 24 fps sequence I'm back where I started. No matter what I try, I can't seem to export and re-import 24 fps audio without losing synch.
The finished mix needs to go to a post house for 16mm optical sound, but I have no way of telling if the mix is in synch or even whether the mix is timed to 24 fps (which I suspect) or 23.98.
Any information is appreciated, thanks.

Answer 1

Thanks for jumping in.
I tried to avoid describing the workflow - it kind of defies description at this point. This project originated in 16mm 15 years ago. Most of the picture editing was done in 16mm on a flatbed Steenbeck editing table. Then for reasons that are complex, I switched to FCP and finished my edit that way. To complicate matters, it's a mixed media project bringing together 16mm, super 8 and some video. The workflow is unconventional to say the least, which is why is a shortage of people I can ask about this issue.
However, regardless of workflow, the issue I'm experiencing (specifically as it related to working with FCP) is the following:
When I export audio from a 24 fps timeline and re-import the aiff file back into the same timeline, it is no longer in synch. I've never had this problem working in 29.97 or 23.98, so I'm baffled. I've now tried this with other source footage unrelated to my project and I get the very same result. There must be something unique about working in 24 fps that I don't know about and can find no reference to in the manual.
I invite anyone to try this: Create a sequence (I've tried two codecs: photo-jpeg and DVCPRO 50), set the editing timebase to 24, plop in 30 minutes of video footage, export the audio, re-import the audio and place it back in the sequence. When I perform this operation on my machine I lose synch.
My sequence settings: 720 * 480, DVCPRO50, 48 kHz audio, 24 bit (the editing timebase, of course, is set to 24)
Thanks for your help.