Ford Transit vans are excellent, and popular, base vehicles for campervan conversions. Since their intrduction over 40 years ago more than 5 million transit vans have been made.
Ford Transit's are reliable and proven vehicles. They come is a wide range of styles and sizes. Parts are relitavely cheap and easy to find new, or used from the many vehicles that get broken into spares after accidents.
eBay is a great place to look for Ford Transit vans for sale.