Its a truck OS thing, all truck OSs regardless of 60E or 80E do this. Annoys the crap outta me on my 02 TB, I run a pretty aggressive ramp up rate to try and have it lock as fast as possible, but its still annoying.

For the SS and all T42s, you can get around it by running a car OS in the TCM. Not sure you can do it in a LS1 as the platform options might be different, but who knows. Unfortunately, there were no cars with 80Es and doing a seg swap of an 80E trans seg to a car OS will keep the truck OS issue. Boo.