The Wurlitzer Flexible Coupling & Shaft Assembly # 21347 is used in models
P-12, P-30, P-400, 312, 412, 35, Model 400, 316, 416, 616, 616-A, 716, Model 24, Model 24-A, 500, 500-A, 600, 600-A, 700 and 800.

This piece has been taken apart and cleaned.  I then reassembled it using leather discs that are in good condition. 

It is ready for immediate use.

This assembly is about 3/8 of an inch longer than the # 39614 Flexible Coupling & Shaft Assembly found in later models
750, 750-E, 780, 780-E, 850, 850-A, 950, 1015, 1080, 1080-A and 1100.

This difference in length comes from the center shaft - the end pieces are the same on both versions.
I have included two reference photos here showing the difference in length of the two different center shafts.