I had the Titan replacement tank installed on my 2021 CCSB last week. Have about 700 miles with it and so far so good. The only hiccup was that even though the tank, when installed cleared the rear fuel filter by about 1/8", once filled, it must have expanded enough to then touch the edge of the filter screw on cap. I was worried about rubbing and wearing a defect into the tank and also about easily getting the filter cap off and on. There was just enough play in the frame holes the filter mounts to for a solution. The installer loosened the bolts holding the fuel filter, pulled the filter bottom/cap away from the tank and retightened the bolts. Now there is a clearance even when full. Still the same after 700 miles but the real test will be after miles on washboard road. I am optimistic it will stay good though as the tank is held in place very securely and tight by the Titan straps, and the two bolts on the fuel filter are good size and torqued down well. If it had turned out to not be that easy to fix, I suppose then could have enlarged the holes a bit and moved the filter that way but it did not turn out to be necessary.
I suspect the issue came up because even though Titan supposedly used great detail and lasers to design the tank fit, the fuel filter truck to truck might be mounted off by a fraction of an inch or so. In my case this put it touching the tank, in other cases it might be fine. I don't know how much extra slack, if any, is in the hose and electrical connections to the fuel filter but if on a particular truck it could not be solved just by loosening and retightening the bolts, it might be possible to do this: Remove the filter and bolts and drill a third hole to the passenger side of the two existing holes and move the filter over by that much. The driveshaft is over in that direction but there is a lot of clearance to that on my truck at least so it probably would have worked. Happily we did not need to try that solution though.
It is really something that these trucks meant for towing would come with such small tanks. Going to 52 gallons from 31 may not seem necessary to all but for us, towing in the desolate country of eastern Oregon, Nevada, Utah and Arizona, it will be good peace of mind. Nice to have the extra distance capability to not always have the TT connected when fueling. Also to pass up small out of the way fuel stops for a more heavily used one down the road.