Ok, reading all the posts on the 80's board about extended diff breathers made me crawl up under my 40. Looks like I don't have any kind of breather on it at all, just the nipple. It looks like there is a cap on the nipple coming out of the diff (it's a 74 40 series). Should I put breathers on them. Is that cap looking deal some sort of a valve? Recommendations? The 40 sees more deep water then the 80 does. Last time I swapped the fluid it was looking pretty nasty, thinking this might be the reason.