For the longest time now I have had a really bad thump in the drivetrain that usually occurs when I'm in a gear and give it gas. The issue is too much slack in the drivetrain and when I give it gas it will thump bad until the slack is taken up.

I initially though it was the driveshaft for two reasons, Every thread about drivetrain thump gets directed to Bad Carrier bearings and I had a lot of slack in my driveshaft.

I swapped out the driveshaft with another and still the same issue, I swapped out the read diff and still the SAME ISSUE!!!!

So I checked the Driveshaft again and even the used replacement had a lot of up/down - side/side play. Well I was not going to drop almost $200.00 on new carrier bearings as I was still not convinced it was the carrier bearings caused the thumping. So I took my spare driveshaft and willed in the carrier bearing doughnut with polyurethane. Let it setup for about a week and re-installed it. There is ZERO play in the driveshaft now but I can twist it almost two inches either direct.

Why is there so much slack in the driveshaft? This slack is what is giving me the damn thumping and I don't know how to alleviate it. Any Ideas??