1976 Scamp fuel gauge problems

You do realize that 76 is a one year only electrical system, and the cluster from any other year won't work. There are some real oddities to that system in relation to all other Mopars from that era.
Considering that you're finding all sorts of burned up parts in the trunk, and you're going through the trouble of changing out clusters, you might want to consider converting the car to more common 1975-back electronics. it may seem like a lot of effort and expense, but if you intend to keep that car, it may be a worthwhile investment,