Classic & Vintage - Peugeot frame ID

I have an old Peugeot frame (sorry, no pictures) which I am trying to ID to figure out what kind of bottom bracket it uses. It is red, labeled Peugeot in light blue on the top tube and "Built with Mangalite", "double butted tubing high manganese density" on the seat tube. Any ideas?

That's not much to go one. Are you trying to determine the thread standard, or the make, or maybe something else? Do you know the make and model of the cranks? Are they cottered or cotterless? Are there any markings on the cups? Does the fixed cup have the standard two flats? Anything you notice that is unique about the cups?

Yeah I'm unsure what you are trying to figure out? You know what make it is already, and what its made from... is it a road bike or an MTB?

I am trying to figure out if I can replace the cup/cone bottom bracket with a modern cartidge bottom bracket as the ball bearings are worn out and I am not sure what kind of cranks to use with the old bottom bracket.
In response to the comments above:

I have the frame only - no cranks.
The left (non-drive side) cup is marked "S" only.
The axle is marked "S" on one side in the middle of the axle, and "121" or "424" (hard to tell which one) on the opposite side.
The drop outs are marked "simplex".
The right chain stay is marked "12 vitesses/speeds".
Thats all the markings that I can find on the frame and bottom bracket.
Thanks

Well, if only the bearings are worn and the cups or spindle aren't pitted, you could always just repack with new bearings. If the bottom bracket turns out to be French thread, you could always go with a Phil Wood cartridge bottom bracket. I believe they sell an adapter for use with French threaded shells.

Always a good French bicycle reference:

http://www.sheldonbrown.com/velos.html

You have the spindle out. Were you able to remove the fixed cup? If the fixed cup has right hand threads, then it is French threading. However, if the fixed cup threads are left handed, then it could be either English/ISO or Swiss and you will need to post the markings and/or distinguishing features on the cups.

If it's French threaded and you can't find a replacement, another alternative to Nick's suggestions is to have your LBS ream out the bottom bracket and rethread it to Italian standard.

If the fixed cup has a chrome finish and its left handed its british. if its a yellowish or goldish color its NOT british.

If the fixed cup has a chrome finish and its left handed its british. if its a yellowish or goldish color its NOT british.

Yes, all gold/yellow tinted cups on Peugeots were Swiss threaded. But the converse is not true. All Swiss threaded cups on Peugeots were not gold. There were also Swiss threaded cups on Peugeots that had a chromium finish.