Dynamo for selecting open ended ducts and automatically placing a duct transition fitting on them (+100 in height and width)

Spent the whole day trying to download OpenMEP package but with no luck, so I’ve been trying to find a workaround node for it. I’ve been kinda stuck here for the past few hours as I cannot seem to figure out how to replace the Duct.CreateByConnectorAndPoint node from OpenMEP. Some feedback would be great, cheers!