Does anyone know what the difference is between a 861 and a 861-C 16 size balance staff...

Hello Gary, you sure that's a 861 c, and not 861o,
The 861 is .210 long
The 861o is .204 long
The hairspring side is longer on the 861
But in all my stuff on Elgin I don't show anything about a 861c..

Gary, I did find one thing that might belong to a C.
Someone may have marked those as being a combination type staff, which is used for the staff that uses the combination roller table and safety roller that was made together ....

Paul
I couldn't find anything about a 861-C either...The big red Elgin parts book says this watch does take the C staff....The movement is a single roller escapement...I have a couple old Waltham School Staff assortments I am going to check to see if I can find something..If not I guess I will Try to find something that will work..Thanks for your input...Gary

The only difference between 861 and 861C is an oil groove on 861C. All dimensions are the same.