Looking at both part numbers on Amazon you get nice pictures 1745 has an extra part. https://www.amazon.com/ACDelco-MU17...8&qid=1532731639&sr=8-1&keywords=delco+MU1745 https://www.amazon.com/ACDelco-MU17...pID=31qLo04HGCL&preST=_SY300_QL70_&dpSrc=srch extra part 16238399 - Fuel Pump Tank vapor Vent Pressure Sensor for Acura Cadillac Chevrolet
I have 2 - 99 Tahoe's getting new fuel pumps. Mostly due to the wires being corroded off or chewed by rodents. But anyways... Rear of your tank, back side at the top...... You either have that vent sensor there or on the pump top as shown. Go accordingly. Plus the other options I've seen is a radio interference filter. I just ordered without. And it seems they all now come with the upgraded wiring harnesses, if you don't order one that's already done like that. Can get you pics of mine if you'd like. Its still out of the truck because I need to replace the brake and fuel lines on it.
I will get it figured out, currently waiting to finish installing my car lift to do this job and a few other general maintenance jobs on it.