From PowerBoat Guide:

(a reference book used by brokers, marine lenders, etc)

Wellcraft:

One of the best-known names in the marine industry, Wellcraft traces
its roots back to 1955 when the founders began building several small
wooden runabouts. By the mid-1960's the company had made the transition
to fiberglass, and the Wellcraft line had grwon to a series of cuddy
cabins and renabouts from 17 to 23-feet in length. The 1970;s were an
era of rapid growth for Wellcraft Marine: 1976 saw the introduction of
the Scarab design, and in 1979 Wellcraft produced thier first inboard
family cruiser, the Wellcraft 310 Express. Wellcraft was by now one of
the largest builders of pleasure craft in the country.........

There's more, but that seems to address your specific question.