If I get a 4th gen rear from an LS1 car will the brakes fit with my 16x8 diamond spoke TA wheels, or will I have to get an LT1 or older rear?

 

it's been done, but not all rears or wheels are exactly the same, that said, it shoud go. - Take a wheel and slide it on the rear before you buy it.
- I'm assuming you're talking of a disc rear.

 

It would be disc brake rear. I have heard of people swapping both 93-97
(LT1) rears, and 98-02(LS!) rears into their thirdgens, I know the job involves a brake prop valve swap as well if you are going from a Drum brake car, but somewhere I seem to remember hearing the LS1 Disc brakes won't fit under 16x8 TA wheels, maybe it was the front disc brakes only.

 

- The LS1 rear discs are 13". 13" fronts won't clear GTA wheels, but with rear calipers being considerable smaller, they might. - Like I said, set a wheel on there and check.

 

u can use ls1 calipers with gta wheels i dont know about the frounts