Logic 10.7.4 won't open SD2/SDII Sound Designer Audio files

I have some old analog tape to DAW transfers which used SDII file type for audio.

I can still can drag and drop open them ***in Logic Pro 10.3*** (luckily I had a version of this saved on one of my external back drives) However they don't open in Logic Pro 10.7.4!

I'm wondering if this ability was dropped - forgotten - or has become hidden somewhere -> or requires some kind of specialized open/convert process?

This article talks about SDII files - but drag and drop isn't working for me. In addition to drag and drop not working I also tried New Project(audio tracks)/Import Audio - and all the SD2 files are greyed out no matter what I try.

It's only just by luck and happenstance that I still have the older 10.3 version as well as the new - downloading older versions of Logic doesn't seem easily available via Apple's resources page. A lot of hassle to work around something that was once a feature and now seems gone. I'm new to Logic and was hoping I'm just missing something! :-(

Yes obviously I can open the older version of Logic to be able to create access and then save them into a format that 10.7.4 can read. But that's the worst case scenario and weeks/months of tedious work.

Any ideas?