So I decided to replace my rear axle shafts and was informed it’s highly recommended to replace the diff cover since I have 3.73 gears. No worries, I ordered one and was about to install but then noticed a threaded hole up top, which has access to the inner compartment of the rear end. Plus there’s another threaded hole at the bottom left. Neither of these seem to have any function since the bottom one has no access to any fluid at all, my question is, what do I do with these two holes?

 

what brand of diff cover did you order?

 

It’s a Skyward Product but all specs and if you look at the GT500 Diff cover, it’s exaclty the same.

 

And no instructions? I took a look at their website. From their pictures, it looks like the one on top has a cover plate inside. Might be for some type of aftermarket venting system. I would put a plug in there to make sure you don't get any leaks.

The Bottom one that is a blind threaded hole could be for a temp gauge fitting for a track driven car.

 

I kinda figured the bottom one was for something either temp or brace related but the top was really driving me crazy. Thank you and I’ll have it finished tomorrow and then the fun stuff starts next week.

 

I have what looks like the same cover, that I bought from Don Wood FRP. I moved the axle vent from the axle tube up to that location and plugged the opening on the axle. The fluid is less likely to puke out the vent located higher up like that. You can tell that's what it's for because there's a baffle plate in front of it on the inside. The other threaded hole is a blind hole. Not sure what it's meant for but I just left it as is. I have an axle overflow reservoir connected there and the vent valve was moved from the axle to to the reservoir. I probably don't actually need the overflow reservoir with the vent located there but I already had it installed to stop the tube located vent from barfing lube in hard right handers.

 

I hadn't thought of a suspension mounting point. Given how this fits like 85-2014 models (i think that's what it said), very well possible. looks good!

 

I've since cleaned up the rusty bits and applied some Rustoleum Rust Reformer. New sway bar bushings too: