Only time will tell, but a point from a discussion with Dukes was that
in Cessna (where they’re used extensively) service, the pumps run
forever and only get serviced because of the 10 year rebuild requirement
on the pump. So I have to believe it is *very important* to keep the
Dukes type vane pumps flooded if you go headerless and take the mounting
into account.

 

Charles,

 

Dukes statement is balderdash.  In my Skymaster, the Dukes in the nose gear wheel well operated for at least 25 years.  The one in the rear engine compartment failed twice in that time.  Mine, firewall forward mounted with plenty of fuel head(er), failed after 5 years (seal/diaphragm/shaft leak).  My conclusion (small no. of data points) is that they fail in hot environments.  You should have no problem by putting it under the seat.  I hope you get 25 years out of it.