G.M. uses them for many service splices. They are known as Duraseal splice, has a glue that makes a seal to the wire insulation.

The cheap ones are just that.

Last edited by BC59; 12/18/2021 6:15 AM.
BC
1960 Chevy C10 driver 261 T5 4.10 dana 44 power loc
1949 GMC 250 project in waiting
1960 C60 pasture art
Retired GM dealer tech. 1980 - 2022