OK...Here is a little background on my truck first: I have an 02 Supercab Longbed with the 5.4 and a 4R70W with 18,000 miles. On hard acceleration, just as it shifts, there is about a 1 second really loud squealling noise. I am not sure whether it is tranny or a belt (but I am absolutely sure it is NOT tire spin) but it always happens at the same time. No shuddering like with normal trans problems. Anyone have any ideas?

 

It's most likely your serpentine belt slipping; my 2000 5.4 did this. Goodyear Gatorback>Autozone>$29>stops it completely. Many other members here have discussed this topic.

 

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Thanks a bunch. For $29 I'll try it and if it works...

 

You're Very Welcome !!