I did an axle swap in my chevy and i went to hook up a vent for it and the 90 degree elbow they normally come with is gone, also the threads where the elbow would go are hooped. What are some other options to go with? the diameter is about 3/8 of an inch
Try chasing the threads with a tap or drill out and tap to the next size up. Should be NPT (tapered thread) 1/8 npt is probably what it is. Make sure you pull the diff cover off and put a rag in there to catch the shavings.