Thunbderbird T Handlebars

Hi All
After some advice on the t bar handlebars and the kit - now discontinued but was # A9630044. In the kit there is a plate which fits between the upperside of the yoke and the bottom of the legs of the bars, part # A9630118, # 4 in the image. The bolts coming through the bottom of the yoke, through the plate and into the legs, securing the whole lot. My question is, how crucial is the plate, its proving a real PITA to source !
Any info appreciated.

Cheers