If you own an MGB that hasn’t had its sills replaced, there’s a good chance that it either needs them now or will at some point in the future. The purpose of this document is to introduce you to the MGB sill structure, explain why and how it rusts, answer some basic questions about sill replacement, and provide some resources for additional information.
A very comprehensive article with everything you need to know about MGB sills repairs …… https://www.mgexp.com/article/mgb-sill-repair-and-replacement.297
MGB tips mods and maintenance 