Track says it is a good fit for both the 1860 and 1858. It fit my Pietta 1860 almost like a glove, but... it is a little small for my 1858.
https://www.trackofthewolf.com/Categories/PartDetail.aspx/421/1/HOLSTER-SJ-R
https://www.trackofthewolf.com/Categories/PartDetail.aspx/421/1/HOLSTER-SJ-R