HeinOnline has recently announced the availability of the Code of Federal Regulations (CFR) from inception in 1938 through the 1983 edition. It includes all editions inclusive of this period as well as all supplements for this time frame in PDF format.
Currently, the 1938 through 1983 editions of the CFR in HeinOnline have been electronically indexed to the Book level. Additionally, content from 1938 through 1949, as well as 1977 through 1983 has been electronically indexed to the Part level. In future enhancements, all content will be electronically indexed to the Part level.
Note that the CFR is available from 1996 through the present at GPO Access.