I have several partial sets of rings. I will have to look and see if I have .040 oversize. Do you need a plain cast ring or a premium molly ring? I wouldn't worry about a different brand ring on one piston as long as you use all 3 rings from the same brand.
EDIT: Sorry, can't help. I have .020, .030, .060 open sets, but no .040
Thanks Charrlie and everyone else, ill buy the engine tech set and use the set on the one piston. Maybe ill write down which one and we can see the longevity of USA rings vs China rings on my next teardown.
