The FM was made by Nikon, while the FM-10 is the standard Cosina SLR body with a Nikon F mount and whatever features Nikon stipulated Cosina was to add to it.
They are two different cameras, from two different manufacturers so I'd assume that the DOF levers are not interchangeable.
There is an FM-10 DOF lever for sale on ebay (but no FM DOF levers) for about $6.50 US, and KEH currently has a bargain grade FM body for about $35.00 so it really won't cost much to get a replacement body.