Telescope missing a mystery part

I found this beat-up Celestron PowerSeeker 70AZ in my aunt's old stuff and it was missing the entire eyepiece section. I work with an astronomy research group, so I have no problem finding a set of 1.25" eyepieces and a diagonal, but the piece that converts to the 1.25" mount from the focus tube male thread (see picture) is also missing and I have no idea what kind of part it is!

I thought it was T-mount at first, but it seems to be something like M40x1.0 instead (40mm thread OD and 1mm pitch), but I can't find any parts with those specs anywhere. Does anyone here by chance know of this kind of part? Or have any ideas for how I can hack something onto it to hold the diagonal?

Any ideas would be much appreciated! (I hope I flaired this correctly)

I found this beat-up Celestron PowerSeeker 70AZ in my aunt's old stuff and it was missing the entire eyepiece section. I work with an astronomy research group, so I have no problem finding a set of 1.25" eyepieces and a diagonal, but the piece that converts to the 1.25" mount from the focus tube male thread (see picture) is also missing and I have no idea what kind of part it is!

I thought it was T-mount at first, but it seems to be something like M40x1.0 instead (40mm thread OD and 1mm pitch), but I can't find any parts with those specs anywhere. Does anyone here by chance know of this kind of part? Or have any ideas for how I can hack something onto it to hold the diagonal?

Any ideas would be much appreciated! (I hope I flaired this correctly)