I've noticed that some of the Winnebago Class C Motorhomes on Ford E-series chassis have a wheelbase which is not listed as available in the Ford E-series cutaway data.
Specifically the 25B has a wheelbase of 182", but the Ford placard on the door jam lists the 158" WB option. And I can find no Ford cutaway data that lists 182" as an available wheelbase option.
Yes, Winnebago lengthens various Ford chassis on many of their models. They even used to shorten certain high GCVR Ford chassis to get the capacity they wanted on a shorter coach but not sure there are any like that right now.
Ford has guidelines on how to lengthen / shorten that Winnebago follows. They have a chassis shop with laser alignment equipment in Forest City that does it.
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Randy - Manhattan, Kansas
2015 Vista 27N
2020 Ford Escape Hybrid
Just as a For What It's Worth comment:
I'm just old fashioned enough to not trust anyone but Ford on how to construct/mess-with one of their chassis including install a longer driveshaft that will never vibrate.
I don't even completely "trust" the small extension that Winnebago welds onto the end of the stock Ford frame so as to provide a trailer hitch. I have to live with that on our small Itasca Class C ... but don't tow anything heavy with it, either.
So if you get under your rig. And look at the frame. You will notice that the frame was cut and extended 3 or 4 feet. They weld in a piece of channel to do this. The welding job on ours is scary as heck. I was a welder for many years and we called welding like that bird **** welds. Because it looks like bird **** instead of a good smooth weld. One side is perfectly welded the other side looks like a beginner did it. But lifes been long and if i go out because of a winnebago welding job. The family will be taken care of after the lawsuit.