I haven't heard that one. When I was in Moab in May I got to visit with Marlin (Marlin Crawlers) and he was in the process of prototyping a setup for the 80 series. BTW, his 4 transfer case mini truck is VERY cool.
I have a set of these low tcase gears for my 80 at the shop. We have not installed them yet. It's not going to be the same bang for the buck you get with the Pickup gears but it will be an option. It's aprox 30% lower range and will cost around $1000 for the set.