Rear end sliding when I hit a bump

[8Ball]

I just put a 3.45 diff in my car about a month ago and recently my car is kicking the rear end out when I hit a bump or go over standing water. The tires over the past week are shredding the tread. I'm wondering if anyone has ever had this issue or know what could be causing the problem

[WhatNext]

Your alignment is out of whack.

[-Ray-]

Thrust angle must be way off.

[Gordo]

I just installed 3.27s in mine. I know exactly what you are talking about, i’m Thinking alignment too since removing the old one required a lot of components to be removed. I’m sure after it’s aligned it’ll be back to normal

[BuildItYourSelf]

Yeah. It's good. To mark everything you take off to get you close enough until alignment day.
Im willing to bet your upper control arms outer bolt is on one end of the slot. The slot is pointless and not needed. Some of us welded a washer on the outside to prevent the bolt from moving at all.
It also sounds like you have a toe issue.
If you can see it in the tire in a short time something maybe wrong. A cam bolt in wrong or something. It shouldn't have been out that bad to remove the hub and re install.