To copy slides, a FX camera is seeking a 1:1 magnification (1.0 reproduction), and a 1.5x crop DX camera is seeking about a 0.67 size reproduction (1/1.5x crop). So speaking of a 60 mm macro lens, DX with ES-1 requires extension in front of lens to position slide farther forward (less enlargement). FX possibly may need extension tube behind the lens, for greater enlargement.
Here is the Nikon instruction sheet for the Nikon ES-1 Slide Copying Adapter, designed for FX users. It is designed for a 55 mm macro lens on a full frame body, but it can be used with DX cameras with the proper spacer between lens and ES-1. The marked note under the chart says 60 mm macro lens with no extension tubes will do 0.96 to 1.0 reproduction (FX). 0.96 is a slightly smaller image, which includes all of slide, but may need slight cropping around it afterward. I am making things up now, but exactly 1.0 may not allow cropping in the camera, so possibly may not be able to eliminate all of the slide mount, i.e., image from 6 mm FX lens works, but may need subsequent cropping either way? Adobe RAW easily crops many images in one operation, which should handle it conveniently. But a little more ES-1 range could be good, and the chart explains that an extension tube behind the 60 mm lens increases the width of its range, allowing cropping choices in camera. The PK-13 is 27.5 mm long, and produces 1.6 reproduction, which is much more than needed. The lens alone already does 1.0, so the shortest extension tube ought to increase the 1.0 number very sufficiently. The Kenko extension tubes support Auto Focus, but the Nikon tubes do not. Again, this section is speaking of FX, not about DX at all.