Hey guys, got a question about my personal vehicle. It's a '00 extended cab swb 4.6L with 4r70w trans. I have a Hotchkis TVS 2/4 kit on it. It's been lowered 3 years now and I've never had any real issue. But I started noticing a small vibration through the floor so I took my driveshaft out to be balanced and new U joints installed. Ever since then I've had an audible "hum" from the rear whenever I go over 75mph. It only does this under load (hill, etc) and I don't hear anything until then. The driveline shop told me it was my pinion angle and I've tried shims with only slight improvement. Has anyone run into this before? I'll replace the driveshaft after I do a motor and trans swap down the line, but it's out of the budget for now. Any help would be greatly appreciated!

Andrew