WIKIPEDIA: Toyota and the Winnebago Company formed a joint venture to develop a mini-truck version of the 4 wheel drive recreational vehicles which we now call SUVs. Toyota supplied bare pickup truck chassises without a bed and Winnebago created an all-fiberglass body to go on the rear. This vehicle was called the Trekker [1] and was the predecessor of the Toyota 4Runner. The production run with Winnebago lasted from late 1979 until late 1983.

Concurrent to the Trekker production run, Toyota was working with other vendors on similar prototypes called the Toyota Wolverine and Toyota Blazer. These very rare trucks are similar to the Trekker, but have subtle differences.

In 1983, Toyota took over production of the Trekker and renamed it the 4Runner which first hit the streets in October 1983 for the 1984 model year. Toyota jettisoned the fiberglass body design in favor of steel, but they retained the removable fiberglass top.