Hello, new to this site here. I have always been a import car guy (sold my 240sx sr20det swapped car)but decided to grow up and got a 68 firebird. It has a 5.3ls swapfrom an 2004 Tahoe already done to it but needs a lot of work, like alot. Question I have is they told me the rear axle is from a 2000 Chevy S10. It does have rear disc but can anyone tell me why they would have put that rear end in there? From what I have found it luckily has the same wheel bolt pattern but uses different lug nuts than the front stock firebird front end. Any help or insight would be appreciated.

I added a picture of the LS swap for the heck of it. Thanks