Does the addition of a lift axle on a used truck less than 33,000 pounds GVWR trigger FET?

We purchased a 2009 used truck that has a GVWR of 32,900 pounds. We want to add a lift axle to the truck and re-sell it at retail. After the addition of the lift axle, the truck’s GVWR will be more than 33,000 pounds. The cost of the lift axle is far less than 75% of the price a comparable new truck would sell at retail. Is it true that our sale of the modified truck will not trigger Federal Excise Tax (FET)?