Have done both successfully without issue on my 69/3.2. However, there is a 3rd way using the mid-70s sender:
3.2 rear location, 18mm thread (no adapter), 0-10 bar sender: 911-606-111-02
Pelican sells it:
https://www.pelicanparts.com/More_Info/91160611102.htm?pn=911-606-111-02-M253
(Amazon had it when Pelican is out of stock, as when I needed it: 911-606-111-00)