proportioning valve question for disk conv

[SS68]

i have a 70 c10 i bought a performance online disk brake conversion kit and a booster and mastercylinder from autozone to save some money. i bought both a proportioning valve made for disk conversions, and a adjustable valve for the rear lines. problem im having is the proportioning valve i bought haves 5 holes for lines to go in. but i only have 4 lines to plug into it. i pulled this picture from the faqs ive been reading to answer my problem and noticed this small piece on top that i dont have. any help on this? thanks