Maybe 3 hours tops on unit. Bought in April so you will have 3 year no fault warranty until April 2019. I ran one on My HPDI 250 for three years and 2 months with no problems (until I hit a stump). $845 new plus $90 shipping and handling.
Most questions are answered on SEI's web site. They also have great tech help by phone.
My loss your gain $600. $85 on you to ship