Don't think it's there. I think the F53 class a chassis was the same way if I remember right, but hadn't crawled under one in a while. Not surprising. This has been a topic on several forums and you'll see the same results there, at least on the later models. The older ones did in fact have one on the frame rail under the driver's door. I don't know what year they changed.
John and Rebecca Dickson
Emma-7 / Little John-5 / Iva-1
Full Timing Again, Rev B
2013 Ford F-350 Lariat CC LB PSD
2015 SOB TT - With OC's Awning Poles (#8)
At least in Heaven, RVs will be perfect, and I won't have to keep fixing them.