Truck looks like it's either had an engine replacement or transmission replacement at one point in it's life,as the bell housing bolts have definitely been wrenched on,and one of the hard lines is out of place,so probably the replacement engine had the block heater,and your truck being Seattle based might not of had the block heater,so it wouldn't have the cord for it. You can buy the cord and install it,if you want the block heater to work