Spidy,
First things first...
To attach an image to a message...
At the bottom of the screen you'll see a section marked "Additional Options", the second box "Attach files" click the "Manage attachments" and a Pop up menu will allow you to upload image images. Note the image size limits.
OK.. the original image you linked was an adaptor with a male external thread? This thread looks like the SCT rear port thread?
All SCT's Celestron, Meade etc have the same basic male thread at the rear cell.
(There's a 3.25" thread hidden underneath the rear cell thread of the Meade. Used by things like Peterson's Eye Opener attachment
https://optcorp.com/products/peterso...acf-telescopes)
Obviously the 2" nosepiece wouldn't fit the rear cell male SCT thread.....
It sounds like your COAG has a female SCT thread(?) why not directly attach that to the rear cell? I assume it's one of these, do you have all the attachments??
https://www.bintel.com.au/product/ce...v=322b26af01d5
You may be looking at the front of the nosepiece...this has a 48mm filter thread, for 2" astronomical filters.