The Morse body is 1/4 inch wider than the others, as confirmed on this EBMM website in the specs. It may be the same length, but I doubt it. Can't tell as EBMM doesn't list body length as a spec. I would think the Morse body (not Y2D) is slightly longer than the others, because of the pup arrangement. Without a doubt the Sub 1 body is EXACTLY the same dimensions as a Silhouette Special, this is 100% confirmed fact my friends. And the Silhouette Special neck profile is most likely identical as well, and in my experience feels exactly the same. And I've played a few Silo Specs.
Because the Silhouette has a 24 fret neck I would think the body might be a tad shorter than the others, because the total guitar length is the same as the Sub 1 and Silhouette Special. Or the body is the same length and the neck is set-into the body a tad deeper. The Morse overall guitar length is 1/4 inch longer than the others (see the specs) and this is due to body length I presume.
Give this some thought, investigation, and look at the specifications on this website in the Instruments section.....
Sub 1 - Size:12-1/4" wide, 1-3/4" thick, 36-1/2" long (31.2 cm wide, 4.5 cm thick, 92.7 cm long)
Steve Morse - Size:12-1/2" wide, 1-3/4" thick, 36-7/8" long (31.8 cm wide, 4.5 cm thick, 93.7 cm long)
Silo Special - Size:12-1/4" wide, 1-3/4" thick, 36-1/2" long (31.2 cm wide, 4.5 cm thick, 92.7 cm long)
Silhouette - Size:12-1/4" wide, 1-3/4" thick, 36-1/2" long (31.2 cm wide, 4.5 cm thick, 92.7 cm long)
The Sub 1 and the Steve Morse bodies are made of poplar. The Silo and Silo Spec are alder. Thus the Sub 1 may have body resonance and weight similar to the Steve Morse.