I have one in my 6.1 Hemi 1969 Barracuda. I was #4 on the "list".. https://www.hemmings.com/stories/article/modernized-mopar-1969-plymouth-barracuda

Make sure you use a manual transmission GL4 oil and not GL5. Mine is a little notchy going into 3rd when cold but otherwise it works great.
HOWEVER, others have experienced significant problems https://www.forabodiesonly.com/mopar/threads/a855-5-speed.442999/