didn't need one on mine. it was totally bolt in. the newer master cly has a shallower rod hole but the adapter plate used to mount it makes the 73 style rod fit perfect.
Try grabbing your pedal and pulling it towards the seat, all the stock rods I have seen will fall out of the master cylinder if this happens, they are about 3/8" short because of the adapter. there is only an O ring that holds it into the master cylinder, it is pretty snug but it wouldn't take much for it to pull out and loose your brakes.