I extended all my breathers up to my firewall today. Thanks to Beowulf for the writeup on SOR. My '97 (July registration off Carfax), has the "new" front diff plastic breather filter. The rear breather was the same design as my 40. I didn't try to disassemble the front breather since it was mostly plastic. Near as I could tell, there is two way airflow through the filter connected to the front diff (ie no check valve). Please don't ask how I know this. I used it as the "final filter". Am I correct in that the "newer" design does not need mods like my 40 (or the rear diff breather if it was used)?