Silicone. Just remember that silicone seals by adhesion, not compression, so both the carrier and housing need to be completely clean and oil free. It compensates for uneven surfaces, nicks, and scratches as well as sealing around the bolts.
Permatex makes an RTV specifically for gear oil. It's works quite well. Just used some last weekend. Hope that helps.
Sealing As most here know , I'm a geezer Mechanic who pre dates RTV Etc. by a fair goodly bit but , my Son hipped me to using RTV's & Silicone sealants in many cases makes for better sealing as well as neater works and longer lasting . The surface must always be HOSPITAL CLEAN , by this we mean wire brushed until all vestiges of old gaskets , sealants , dirt , rust and etc. must be gone then you use some alcohol on a clean rag to fully de grease both sides of the joint including those pesky studs sticking out . Then , spread a tiny bead of sealant along the dead center of the sealing area so as you button it up and the sealant mooshes , it won't dibble into the machine , very important as tiny balls of sealant will plug oil galleries with disasterous results . The bead of sealant almost never needs to be wider than 3/16" , this is very narrow . Permatex makes a most wonderful stuff called " THE RIGHT STUFF " and it's available in tubes or Foo-Fo cans , once you try it , all the others will go into your trash can . I use it on all the pumpkins I change out and that's about 5 every 12 months . So far , none weep much less leak or drip . I use it on full & semi floating axle to hub flanges too .
I always put a thin coat of RTV on the surface, let it set up for a few minutes to form a 'skin', then assemble so there's a little body to it.. On another note, Nate, You're so knowledgeable on everything about these trucks, and a lot of other stuff, I'm wondering, given your frequent references to what you're currently working on, What work do you do currently? Hope you don't mind the prying.
Wait To Retire..... I'm a Civil Servant now , I buy parts & tools for The City Of Los Angeles . Just Monday , they moved me down into the basement where all the junk gets sorted out then sold as scrap . I greatly miss being a Journeyman Mechanic but i still tinker on my oldies , thing is , I work for a day then I'm sore for the whole next week . I worked , played and lived far too hard and now I'm just another broken down old man , glad I can ever be of any help to others as so many were to me when I was coming up .
used the silicone. new to me diff goes a wee bit faster- about 60 mph. my guess is I got the 4.11 diff.
