yes. One of the Tubes, I believe the upper on the Jr Emperor, is slightly shorter than the upper tube on the junior gent. You can use the tubes from the Jr Gent but you end up with a slightly longer pen due to the size of the cap and centerband components on the jr Emperor being larger/longer. Also, the lower barrel on the Jr emperor uses two bushings the same size, while there is a taper to the the Jr Gent that involves using a smaller bushing for the end cap than is used for the center/nib end. There's also a few thousandths difference between the cap bushings of the two kits, I believe either .002 or .003, but that can normally be worked around.