Almost all 16-inch Gibson L-5s have a narrow, pointed neck heel as do the earliest 17-inch Advanced models. By late 1935/early 1936 this was replaced by a wide heel with rounded shoulders, which Gibson continued to use through the late 1930s and into the early 1940s. Around 1939, the heel shape became rounder, and this profile persisted through the mid 1940s. Outliers can be found with a rounder, almost semi-circular profile while some early L-5Ps (cutaway examples) have a shallower neck heel.
Bear in mind that the heel shape – like the neck profile – varies to a degree from one example to another, no doubt reflecting the fact that much of the shaping work was still done by hand during the pre-war period.
1. L-5 serial number 87060, which was shipped 1931, displays the narrow neck heel typical of virtually all 16-inch L-5s as well as the earliest 17-inch Advanced models.
2. L-5 serial number 92605, which was shipped 1935, has the wide heel with rounded shoulders typical of Gibson L-5s dating from the mid 1930s through to the early 1940s.
3. L-5 serial number FA 5166, which was shipped in 1940 has the rounder heel used through the 1940s.
4. L-5 serial number 97986, which was shipped in 1944 has a much rounder, almost semi-circular outline.
5. L-5P serial number 96204, which was shipped in 1940 has a shallower, rectangular neck heel (compare this heel shape to that of L-5 serial number 92605 above).