I am guessing that you have HWH levelers on your coach. Contact HWH and tell them the year and type of levelers you have. They can likely tell you what spring you need, or will advise you how to determine which one. They are extremely helpful. They can probably provide the correct spring at a cost equal or lower than you will find elsewhere.
Tom and Barb
'07 Winnebago Voyage 35L
Workhorse W22 chassis FMCA 219315