Maybe we can work on identifying screwdrivers we are on the lookout for with some investigative work. So far we know the IRWINs started with ink stamps on the handle and nothing else, making it hard for us to identify one that LOOKS like an IRWIN but has no discernable markings on the handle. the BIG question we need to answer is...were there OTHER makers who used a design close enough to mistake them for IRWINs or did they have a unique enough design to make the ID possible with no ink stamp left?
This issue with the ink stamp all raises the question about any other period correct screwdriver with no discernable marking on it...could TOBRIN or FURNEY-SHIRWIN or FAIRMOUNT also began production with a marking that could be lost over time?
Let's start with the obvious:
IRWIN...you can find plenty on each of the various ones with ink-stamps or roll-stamped shanks in the posts on the g503. The Ink Stamped style has been verified and the others are still MAYBE for a WWII jeep.
TOBRIN....noted on the Willys drawing... they were marked in the 1930s with the SIZE on the tip so the ink-stamping question is a moot one with the TOBRIN. Look for the barber-pole roll-stamping on the shank.
FURNEY-SHIRWIN: We have not seen one of these, so maybe the FEDERAL note refers to their trademark or the marking on their products. (see FEDERAL below).
FEDERAL: In looking at Jeff's FEDERAL marked examples, note that the ends of the wood slabs are half-moon, almost rounded where as the IRWIN are different. You can compare photos to see that it would be easy to tell the IRWIN from the FEDERAL. I say this because the FEDERAL seems to have been produced with a name that is actuall STAMPED into the wooden slab. Sanding would eliminate that of course and if EARLY production was done with an ink-stamp it might be missing today. So the FEDERAL needs a bit more investigation. I have a pic of another new-looking FEDERAL roll-stamped on the shank but....it looks to be the IRWIN design! (I think they merged post war...anyone remember that???)

- Federal Screwdrivers JAB.jpg (97.11 KiB) Viewed 965 times
FAIRMOUNT: Ah yes! The "missing link"...no one has posted a pic of one to my knowledge....so a theory here of mine is that perhaps they were produced with an ink-stamped marking and over the years that was lost. So a FAIRMOUNT could be mistaken for an IRWIN or perhaps another mfger who used an ink stamp...
So let's look into the ones with NO marking on them...
First the IRWIN is the same as roll stamped IRWINs, but any other mfger who used that design could have an ink-stamped one of their mistakenly identified as an IRWIN.
The TOBRIN....as far as the 1930s they put the size on the blade tip so you can't mistake an unmarked one for a TOBRIN. In addition, the TOBRIN has a uniquely DIFFERENT shape to the wooden slabs from the IRWIN!

- Tobrin Screwdriver Handle.jpg (24.74 KiB) Viewed 965 times
The FEDERAL by the way, seems to mimic the design of the TOBRIN. Therefore, an unmarked screwdriver that has that TOBRIN/FEDERAL deisgn is NOT a TOBRIN since they put the size on the blade!
I am listing Roger's VLCHEK because it is the SAME design as the TOBRIN/FEDERAL. It has the stamped-in marking on the handle.

- VLCHEK Screwdriver Roger.jpg (33.28 KiB) Viewed 965 times
So...we have nothing on the FURNEY-SHIRWIN so if Fred's theory is correct then the F-S is the one we see marked "FEDERAL". I believe his idea is the right one! Unless someone has one so marked? Can anyone post a pic or two?
Then we have the FAIRMOUNT...same thing, no known example has been posted so it may be of either of the above styles or an altogether different design.
I own a LENOX with a sideways "6" and the name on the shank...for next to nothing I could not resist. Joe Potter told me he found one like it in the tool box of an MB he purchased...and it is otherwise close to the design (a slimmer shank) with the design of the slabs of wood CLOSE but not EXACTLY like the TOB/FED/VLCHEK design. I include it so we can use it to identify others...is it correct? Who knows, I doubt it.
If others can post pics of any others or especially of the ones we don't have pics of above (FURNEY-SHIRWIN or FAIRMOUNT) or even others, we can maybe make it possible to identify for sure those that appear unmarked.
I have another thought about this:
We know VLCHEK was a supplier to many other sellers such as Western Auto Stores, or even car companies so I am not ready to rule out the idea they produced some screwdrivers for some of the companies we have listed above!!(Edited with Fred's post in mind...thanks!)