I have a small block 350, with tbi in my 84ish square (cab is an 87, bed is an 86). My header flanges lay on the pavement, then again the truck is bagged. I am not sure of the headers that I have. I bought them from my local hot rod/speed shop. Anyways...the flanges hang approximately 3 inches below the frame rails...very similar to the specs of the Hooker headers. I was able to install the headers without seperating the motor mounts. With the Hookers, you too should be able to mount them the same way. The only concern is clearance between the header and the inner part of the frame rail on the passenger side. I had to notch my frame about 1" in order to,keep the header from wearing through from vibration and normal movement. I was told that these unknown header are the same specs as Hookers in every way except price and that these headers were in stock when I was in the shop. Fwiw...you WILL NOT need a heater O2 sensor in the headers. I went through this and it made no difference. Dont waste your time and money installing the sensor.
Before my square was bagged, it had a 5 front 7 rear drop and with the headers installed, I had plenty enough clearance not to ever drag them...even on the occasional speed bump.
