The AG rear derailleur was specifically designed for the 38. One would think the triple-pulley rear derailleurs like the LePree would handle the 38 well, but my experience wasn't all that great. Several of the very long cage index Shimano derailleurs made around 1988-1992 shifted the 38 very well. This was long before the existence of cheats useful accessories like the Wolf Tooth Road Link derailleur dropper, which enables a wider range of rear derailleurs to handle decent-size rear sprockets.