NP231J Rebuild
 

I need to rebuild my transfer case and see a lot of options for kits. Most are just the seals, bearings and gaskets, I've seen some that come with a new chain. I haven't tore my TC apart yet to see if the chain needs replacing, is the chain something that typically needs to be replaced during the rebuild? I've considered ordering the kit with the chain and just replace it as a precaution but shipping to Hawaii limits my options for those kits for some reason.

It is not typical to replace your chain, unless there are other issues. There are many tips on line but, Seals and fluids should do the trick .

What?

Yes the chain. It wears out. It "stretches". If you're going in the transfer case, replace the chain.

Edit:
I installed this kit in my brother's TJ. It's been great for 10k miles so far. I know that doesn't prove the test of time, but I was fairly impressed, especially for the price.
https://www.ebay.com/itm/Jeep-231-Tr...f-19abc6d45503

Well your in luck as I've been going through this exact same thing. My TC needed a rebuild too and I can definitely suggest bone up on lots of you tube videos and stuff from here before starting the whole process.
I purchased the kit with everything and used the vast majority of it. The chain in mine was not stretched all that much but this is a sizeable amount of time invested, so it was done. Get a good set of flat snap ring pliers because there absolutely necessary.
Patients is king!

Proto J250G Proto 9-Inch Lock Ring Horseshoe Washer Pliers