Late 3.8 and all 4.2. The wood is laminated from 5mm strips of Mahogany, bent around a jig and then machined as per original. Restoring your original wheel is quite straightforward to do, and a very satisfying project. I recommend a high strength Epoxy for this job, such as System Three T-88.
It should be made doubly clear, that the aluminum wheel in the photos is not included--This is new wood to restore your existing wheel, and the photos showing partial/restored steering wheels are examples only.