Mark Sanchez -- Getting Help from Dad for 9/11 Fundraising Mission

NY Jets QB Mark Sanchez is marking the 10th anniversary of 9/11 with a new fundraising campaign to benefit the families of fallen NY firefighters ... with a little help from his dad (and Ron Howard).

Mark -- who moonlights as a GQ model -- has designed a new vintage-style designer t-shirt and has put them up for sale ... with 100% of the proceeds benefiting the families of fallen firefighters via the New York Police & Fire Widows’ & Children's Benefit Fund and the FDNY Foundation.

The shirt features the slogan "You Go, We Go" -- a line suggested by Mark's father Nick Sanchez ... a veteran firefighter ... and obvious fan of the Ron Howard movie "Backdraft" ... where the quote originated.