The bumper on my 81 van looks like the K5 and pickup ones(the front does too)but I know the bolt holes are in different places,and the brackets are very different too--but you could drill new holes I suppose,but you have to plug all the leftover holes,or have a swiss cheese looking bumper,and I'm not sure if the overall width is the same.
Too bad your not nearby,I have a stock(not step and tow)bumper from a 73 fleetside leaning up against a tree in the backyard!. /forums/images/graemlins/crazy.gif Our boneyards here sell them cheap,about 30 bucks if you pull it yourself. /forums/images/graemlins/grin.gif