Looking For Replacement For Curt Rota-Flex Pin Box On 2021 XLR Thunderbolt 5th Wheel
Updated 12/22/2025 | Published 10/03/2024
Question:
I have a curt rotoflex fifth wheel pin box on my 2021 xlr thunderbolt firth wheel. I am trying to remove the pin box and install a gooseneck adapter/hitch onto the camper. I need the hitch to be rated at no less than 24k pounds. What hitch/pin box works with with replacing the rotoflex.
asked by: Caleb G
Expert Reply:
Hello Caleb, thanks for reaching out. We certainly should have a replacement pin box option for you, but the Curt Rota-Flex pin box can use of several different bolt patterns, so I will need a bit more information from you in order to recommend the correct replacement.
Specially I will need to know the pin box size or bolt pattern that your current pin box uses. There may be a sticker on your pin box that says the serial number and model number. This sticker may also indicate the bolt pattern. If not, we should be able to use the SN and model number to determine the size.
If no sticker is present, you can use the guide I linked below to measure the bolt hole spacing and determine the size. Drop that info in the comments below when you have it and I am happy to look into it and make a recommendation.
Product Page this Question was Asked From
Curt Rota-Flex 5th Wheel Pin Box - Lippert 1621 - 21,000 lbs
- 5th Wheel Pin Box
- Upgraded Pin Box
- Absorbs Road Shock and Reduces Chucking
- 21000 lbs
- Rubber Spring Suspension
- Fixed Turret
- Lippert 1621
- CURT
more information >
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on 5th Wheel Pin Box
Jesse M.
12/22/2025
Hey Caleb, were you able to find the model number or bolt pattern on your Curt Rota-Flex pin box? Once you have that info, I can help narrow down a gooseneck adapter rated for at least 24K. Let me know what you find—I’m happy to help.