Notes on a forum topic elsewhere on the web, images follow below.

The forum topic first suggested that the derelict airframe in the photo below might be a Bell X-2. Responders quickly identified it as a Douglas D-558-2 Syrocket, following debate correctly noted that all three Skyrockets are accounted for in 2 museums and 1 college.

My opinion is that the airframe in question probably is an engineering mockup of the Skyrocket.  Here's why...
The first configuraton change was from a flush canopy to a raised canopy. The #1 Sk;yrocket was built in 1946 with a flush canopy, generally similar to that of the Bell XS-1, later redesignated the X-1. The change to a raised canopy occurred before the Skyrocket's first flight. The airframe in question is missing its canopy, but it does not have the modification that added a canopy fairing aft of the raised canopy.

The vertical stabilizer was originally short, with its top at the level shown in the photo. After flight test experience identified stability problems an extension was added to increase the area of the vertical stabilizer. The photo shows a squared-off top on the vertical stabilizer, instead of having the original gradual curve from the leading edge to the top edge. This is consistent with the photographed airframe having been a mockup that was used by Douglas engineering to check structural changes needed to add on the stabilizer extension.

The subject airframe shows a probable third change with room for some doubt because the original photo has a large objuct obstructing view of part of the lower forward fuselage. It looks as if this fuselage is in the rocket-only configuration of the Skyrocket. That was a mid-program modification that involved removing the jet engine and doing related internal changes.

Photo 1 below superimposes the fuselage from the forum-posted photo over a photo of the #2 Skyrocket. The past-over is slightly cut off at the bottom where it was obscured by grass and weeds. Both photos were shot by photographers standing opposite to approximately the same point on the forward fuselage. Minor differences in tail shape appear to be photographic, with the probable mockup having been photograped with a lens of longer focal length than the one used for the lakebed photo of #2. The tilted rectangle at the forward fuselage of the probable mockup is a large obstruction in the photo's foreground.

Superimposed images

Photo 2 is a copy of the #2/lakebed photo with contrast increased to more clearly show panel lines on the fuselage.

D-558-2 Skyrocket #2 on Rogers Dry Lake

Photo 3 is an unedited copy of the #2/lakebed photo.

#2 D-558-2 Skyrocket on Rogers Dry Lake