I've completed my conversion to 6" PVC and have the 4" flex hose
and fitting available. They are USED but in reasonable condition. The
hose and fittings are located in Bucks County PA (between Philadelphia
and Trenton, just off I 95) and are for sale.

4" hose
Two 10' lengths
Two 5' lengths and some 30" pieces

4" fittings
One "Y" fitting
Three "T" fittings

3" hose
One 6' and one 3'

Plus lots of grounding wire

trixie AT energytactics DOT com