What that annoying thumping sound is upon acceleration on the 97-03 trucks? Mine's getting worse and worse and it's driving me nuts! I remember something about a spline needing to be greased but I don't think anyone confirmed that.

 

Yup, teflon grease will do it, but for a period of time, that's all. I wouldn't worry too much beyond that. I had my tranny redone and he musta put this in because it doesn't make any noises anymore.