What purpose would that serve on an IDI anyways? With gassers it's there to reinforce the area where the starter mounts to the trans by distributing some of the torque produced by the starter to the bolts between the engine block and the trans - I've actually seen an AOD behind a 351W that had its bellhousing cracked from the lower starter bolt all the way to the top behind the converter (crack ran kind diagonally up and towards the back) yet the starter worked perfectly fine cause the steel "separator" plate held things in place!
Now with an IDI the starter don't bolt to the trans, but to that massive cast-iron adapter we have between the engine an the trans bellhousing, that adapter actually works just like the gasser thin "separator" plate, so there's absolutely no need for a stamped steel one to go behind it and before the trans...
And by the way, what's the official term for that plate, I keep calling it a separator plate in an analogy with the thin plate sandwiched between the VB and the case of a slushbox, but is there an actual technical term for this thing?