Some time I would like to find a 1# package just to try it with cast Al. Currently I use only 5356 and it performs well. Have yet to have anything come back. I just wonder if it would help with the dirty cast lower units I repair skegs on. 4043 certainly does not do well. I have 9+#'s I will never use. Anyone want to trade 9# for a couple pounds of 4943 3/32"? Shipping would probably make it not worth the effort though.