Upgrade 1981 pickup front wheels to 6 lug 5.5" PCD.

[RAdams]

My daughter has acquired a 1981 Toyota Sunrader RV, which uses the half-ton pickup chassis. Normally, these come with the five-lug semi-float axles and matching five-lug front wheels. At some point (unknown) the rear axle was swapped to a six-lug axle; don't know from what model or if it's semi-floating or full-floating. The previous owner put spacers and five-lug adapters on it, probably so he could continue to use the original dual wheels. My daughter would like to get larger, six-lug single wheels for it and change the front wheels to matching six-lug 5.5" PCD mountings (so she'd only need one spare). My question is: are there other models of Toyota trucks from which we could get six-lug hubs and rotors that would mount on the existing spindles so we wouldn't have to change out everything on the front end? Or is there a better option that would give us the single-spare capability? Thanks.