HI
I have just replaced both door tops, the screws came with the spacers and channels i ordered but are just self tappers about 1/2" long either galvanised or stainless(original), countersunk for all except the front sloping aluminium reytainer which ideallly should be roundhead. I drilled a 2.5mm hole in frame for a tight fit. if you need a bargain door top theres some on ebay
cheers
steve