91 Gal RDS Fuel tank/toolbox combo. This tank is from the vegistroke kit. comes with fuel sender and has built in heat exchanger for running SVO/WVO/Biodiesel. It does have bottom connections for if you just use it to increase your current storage capacity. This tank sells for $1200 new from the vendor. It has been used. PM Your Best offer.

It is this tank but does not have the connection concealed as in the picture
Toolbox Combination Tank - Biofuels Technologies