Anyone know if the third member from a 4th gen v8 fits a third gen v8?

 

Depends on the year. If you have a '82 to '89 3rd gen rear end it will have 26 spline axles. The 4th gen cars all had 28 spline axles. You can use it if you use '90 to '92 axles. This is assuming that the 3rd gen rear end is the 10 bolt and not the 9 bolt.

Also be aware that there are 2 and 3 series differentials. You need the correct differnetial for the gear ratio that you are running.