In another version of emacs the third argument to add-hook can be a
number between -70 and 70, like so:

(add-hook 'find-file-hook 'dmp-find-file-hook 70)

In the version of emacs that I am currently using (26.3) it turns non
nil third arguments to t otherwise leave nil as nil.

Having numbers for the third argument seems like you have more
flexibility in order of the sequences of hooks to your hook variables.

Do I need to upgrade the Emacs version?  Ubuntu tells me I am using the
most up to date version of Emacs.