If you want to lighten that diff even more, try looking for #53219, 1/10 Touring Car Aluminum Pressure Plate Set. It's discontinued, but if you're looking for another hop-up for your M-03/04 here it is, if you can find it...



It's a mouthful, but comes in a card-package like the ball diffs. It's a whole machined-aluminum housing for the diff, 30% lighter than the regular cast aluminum parts it replaces. Also comes with a one-piece thrust bearing too, which is nice, along with Cone washers and screw. It worked for my TA03 diff, but I'm sure the manta ray diff would be the same case.

I have it in my M-04, and man it just shoots down the straightaways. Less rotational mass so it picks up faster, as well as achieve a higher top-end.