I've never seen an internal circlip, looks toe like it fell off the axle and is now jammed in the back and not letting the axle seat all the way.

 

So what's my next move? Ppl are telling me that the v36 model has a circlip in a groove inside the differential

 

Yup definitely a clip in there

 

Update.

Used a magnet tool to center the circlip and the axle popped in. Unfortunately I was using an old oem axle shaft stub and decided to attach the rest of my napa axle because I got to excited lol. Axle is shaking because I never knew axles are matched to stubs soooooo time to replace it with an entire napa axle 🤷🏾‍♂️
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