I just contacted 4 dealers about this issue. I am in a rural area and there is one dealer about 30 minutes away. The rest are about an hour to 1.5 hours. 3 of the 4 dealers were not helpful at all and actually pretty rude, including the place where I purchased the truck. They basically said 'it aint getting replaced until the new filler neck is in stock. Also, you don't get a curtesy car because they are all in use until the end of February." Luckily, at a dealer about an hour away the service manager was super helpful. He said send over the VIN and we will get you a tank and filler neck ordered right away.
I have the 23 gallon tank currently and asked him if there is any way to get the 33 gal replaced instead. I told him I'd pay the difference in cost and labor and if you have to put a 10-15% premium on top do it, if it is going to get the deal done. I probably lost some leverage there, but I am ok with it if I end up with a 33 gal tank that I can actually put gas into. Just goes to show you that the right dealer goes a long way! I dont know how this will all shake out yet, but I'm happy just because he was a nice guy about it.
PLEASE READ: This service manager said he currently has a truck on the lot that wont accept gas at all. It has been sitting for a few weeks waiting to get a tank and filler neck to come in. FOR ANYONE THAT HAS THIS ISSUE, GET TO A DEALER AND GET IT RESOLVED ASAP! No one wants to be stranded at a gas station because you can't get fuel in your truck, especially in the winter.