3rd gen rear in a 4th gen??

will this work.. will it all just bolt in?? my cousin has a built rear with 410s sitting around and I was wanting to try it out..

The 3rd Gen 10-bolt is 3" narrower than the 4th Gen. Other than that, and possibly the issue of disc vs. drum brakes, the mounting points (springs, shocks, panhard rod, LCA's) are identical. You would need wheels with 1.5" less backspace, or else high quality bolt-on spacers. You would also lose your ABS, since the 3rd Gen rear won't have the reluctor gear or the sensor on top of the housing.

not to mention the lug pattern is also different....

but yes it can be done, either buy some rims with a zero offset or get a set of wheel adaptors.

WTF ? lug pattern is no different at all, it will bolt in, you'll need bolt on adapters which are 1.5" thick, plenty of 3rd gen guys are running 4th gen axles, with the wheels and then spacers up front, some running regular 3rd gen axles with the 1.5" spacers to use 4th gen wheels on their stock rear.