If you just got the codes on their own with no sense of slippage. I'd say you had a sensor or wiring harness issue. But slippage is an indicator of things to come. Get that truck into a good transmission shop and have them repair the issue. When mine did this, I ended up needing a reman'd trans ($2940 installed with new trans cooler). Hopefully they can dive into the trans, fix what's failing and get you back on the road.

When I cooked mine, I smoked it so badly there were no forward or reverse gears left functioning. It slipped in all. But I was able to drive my truck for nearly 400 miles so I could get home for work and get it repaired. So a shop rebuild wasn't an option.

These trucks do a great job plowing, don't they? What's the set up on yours? Mine's a Fisher 7.5 standard duty. It's getting a real work out this year, heck, it will be pushing another 15 plus today...

Hope you get the trans fixed quickly so you can push more snow!!!