So the other day I was coming home from work, the car drove fine in 1st, 2nd, and 3rd gear. When I hit 60mph whether in 4th or 5th gear my car would bog down and my rpm gauge would stop moving and my acceleration would almost be non-existent. There’s a lot of vibration coming from the rear when this happens and I can feel it all over the car as well as a droning noise. Not too sure what it could be, maybe the rear diff but I’m not too sure. Any suggestions?

My car is a 1990 Nissan 300zx N/A with the 5 speed manual transmission

Unless there is a clear indication that the diff(or something mechanical in the drivetrain) is at fault which would almost certainly materialize at all speeds, not just exactly 60mph. It sound electrical to me, perhaps a bad fuel pump. Is this happening exactly at 60mph, are there any other symptoms?

Sounds electrical, possibly fuel. Check your intake pipes to see if they’re tight and not sucking unmetered air. Check your fuel pressure. Check plugs.

Change your diff fluid if you haven’t ever. It’s good to do, regardless.

Good luck.