Single-size (3.75m) purpose-built shroud for RS-68 engine, to mimic those on the Delta-IV launch vehicles. Will not be available for clusters, and will only be available in a single size.

It could probably be adapted to other engines with some minor modifications. The RS-25 is about the same size as the RS-68, so if you eliminate the cutout/bulge for the turbine exhaust ports it would almost certainly fit nicely. If you open up the bottom of the bulge it might be able to fit the F-1 at a larger stack size (see this image)

As I just added a 'vertical offset' capability to the engine plugin, re-using (or creating a very similar) shroud for other engines is now much more doable.

Will consider creating a few more generic varieties and including those (and the specialized rs-68 shroud) all as the next round of mounts (can usually fit 3-4 per texture).