What's the final word on putting an exta quart of fluid in a NV5600 through the top? I'm getting ready to change mine and was wondering. Some say it makes shifting easier. I'm going to use Amsoil MTF. Also, I tried to get a gasket for the pto cover at NAPA, Advanced, and Autozone. All I ended up getting was a deer in the headlights look at all three places. Is RTF ok or do I need to find a gasket?

 

I would do it. To me the extra quart didn't change the shifting quality. More concerned with the added lube for the upper bearings.
I used RTV for sealing the PTO cover. Don't forget to smear some RTV on the bolt threads too!

MikeyB

 

To add extra I just jacked the truck up from the side and then added it through the fill plug hole. I did have some oil apparently seeping out of the input shaft as I was getting oil on the bell housing. I was using Royal Purple and as the name implies it is purple. The oil I was seeing was purple so I dropped the level in the tranny a little. Just what I have experienced so you may want to keep an eye on this to make sure you don't end up with the same problem I did. It could get expensive if you get the oil on the clutch plate.