4l65e is almost the exact same as a 4l60e, just a different planetary. 4l70e isn't much better at either. Same shit. 4l80e is entirely different trans all together. You'll hate unless you're making 400+ rwhp and have a good converter.
I've swapped my factory 4l65e for a 4l80e. I went through 4 65e's before swapping it. If I didn't plan on building more power later I wouldn't have done it and would've just stayed with a 65e. Now I'm looking to get into the 600+ rwhp and I'm glad I upgraded to the 80e. I also have a 6.0 though. With a 4.8 unless you're going boosted you're gonna want to keep the 60e. If it's having problems it might be time for a rebuild.
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