Lectrolite was the manufacturer, and also used its name for the brand. TruFit was their budget line introduced a few years after Lectrolite wrench production began.
There are many variations in their wrench designs prior to the war, some of it seems to have no rhyme nor reason and is even contradictory. Some are raised panel, some recessed, some forged lettering, some stamped, on and on. For example, the hexagonal shape shank was actually heavier duty and was used in their top-line 4000 series, but here we see the same premium shank being used in a 3000 series under the budget Tru-Fit name (????). It's that crazy.
The shorter 1930s DBE is actually the forerunner of what was to become the standard TruFit design after the war, so that the Top-tier 'Lectrolites' all had raised panels while the TruFit all had recessed. This began around 1947.
Lectrolite made a surprising number of contract wrenches during the 1950s in the TruFit design. I wrote about this at length in a previous thread. Once you learn to recognize them you can spot them anywhere (and just about everywhere!). The contract wrenches will have sequential letter codes (the meaning of which is still unknown), and will often have a forged-in LC for Lectrolite corporation.
The Sears Connection: Starting in the early 1950s, LC made all the recessed handle Dunlap end wrenches (you'll see the LC code on them). In the late 1950s, Sears dropped the Dunlap name on these and just marked them "SEARS" brand, but these continued to be made by LC up until the early 1960s at the Wayne buyout, after which production of these moved to Japan (these are the famously marked "BF JAPAN" tools).
The SK Connection: The relationship between SK and LC began in 1953. Lectrolite was not part of SK, nor did one buy out the other or merge. SK focused on making drive tools. LC was occupied making wrenches. The new raised panel design LC introduced about 1947 were marked Lectrolite until the agreement, after which the wrenches were dual-marked. The 1947 LC wrench is the SK wrench! No difference except for the dual marking. The relationship was essentially that SK would make all the drive tools, LC would make all the end wrenches, LC would benefit from the SK name, and they'd both sell their wares together under the same roof (so to speak). The arrangement was unique. BTW, LC made all the SK adjustable wrenches too.
In 1962, Wayne Industries purchased both the SK and LC companies. Manufacturing continued as before except that the Lectrolite name and brand were retired. The TruFit design was also retired, which is when presumably all the recessed handle contract wrenches ceased. I believe this is why Sears moved to the BF Japan supplier at just around that time.
The original LC 1947 raised panel wrench continued to be made in Defiance and continued to be the SK wrench right through the Wayne, Dresser, Facom, and management-owned years until they went bankrupt and were bought by Ideal, which marked the end of this era and the Defiance heritage.