There is a lot of confusion about tail light lenses for Scout II.
The early design for Scout II tail lights was basically two parts. A stamped and chromed metal bucket with two metal light bulb sockets crimped into place to hold the bulbs. The red flat lens was screwed into the bucket. If your lens is cracked broken or just fading to pink, you probably want to replace it. This type was used from 1971 to 1977. You can find them here.
In 1978 this tail light arrangement was changed to eliminate the metal chromed bucket. IH needed to save money and this is what they did for model year 1978, 79 and 1980. They introduced a new lens and bucket made of plastic. It eliminated the bucket but required new special grounded sockets. Scoutparts.com has a rebuild kit that replaces the sockets. You can find them here.
Here is a look at the bucket/lens combination that IH used in 1978-1980. You can find those here.
