Shipments of converted vans, pickups and SUVs declined a total of 30.9% during July, according to data compiled by the Recreation Vehicle Industry Association (RVIA).
The biggest decline was in shipments of converted SUVs, which fell 50% in July to 500 units, the RVIA reported.
Meanwhile, van conversion shipments from factories to auto dealerships dropped 34.1% to 6,000 units in July.
Converted pickup deliveries also declined 17.1% during July to 2,900 units.
After the first seven months of this year, total conversion vehicle shipments were down 19.4% to 76,600 units, the RVIA reported.
Deliveries of converted SUVs were down 47.6% during the first seven months of this year to 4,300 units.
Shipments of converted vans were down 23.7% during the first seven months of 2000 to 49,600 units.
The only category to post an increase during the first seven months of this year was converted pickups, which were up 4.2% to 22,700 units.