The only files required by the cockpit are:
p_47_vc_map.dds (what I pointed out)
a_gauges_1.dds (gauges)
a_gauges_2.dds (more gauges)
a_gauges_3.dds (yet more gauges)
reticle_us.dds (gunsight reticle)
gunsight_s.dds (don't ask what the hell this is)
rabbit47_t.dds (exterior texture)
rabbit47_r.dds (exterior reflective texture)
The gunsight_s.dds doesn't even exist inside the ETO folder, yet the ETO version works wlawlessly without it, so I doubt it's the problem.
Wait a second... the stock P-47 doesn't have a file named like the one I pointed out. It has p47_vc_map.dds though which means that whoever built the model either used a flawed file name or supplied a different file. You'll find one in the ETO_Hellcat folder or in the shared/ETO_GC and tk_shared folder. Speaking of which we seem to have a duplicate right there.