All synchro's share the same part number--124 262 0034. The same part number applies to 1, 2 3 & 4 th Gear synchro. Your 1st gear synchro is the one in pieces.
The parts have to come from a GOOD dealer. Try to find an older counter person who has worked with the system for some years.

They have to be ordered from Germany, or at the least, a regional center, like Baltimore. The synchro should take 1 week.

I AM REALLY SORRY I COULDNT GET TO YOU SOONER.

The diagram should help.

Please contact me if you need any HELP whatsoever, I'm on the NET twice a day usually,

GOOD LUCK