How I decide what is NOS and what is not

Posted by Andrew Lydecker on

Oh, the joys of unpacking tote after tote of parts.  It's actually fun, but sooner or later, the parts must be listed and sold, and to do that, I must first determine what they are, what they fit, and what condition they are in.  Sometimes this is easy, sometimes not so much.  It can be time consuming, but it's an important step.  Inaccurate descriptions, whether intentional or not, lead to a customer getting a part that was not what he or she believed they were buying, which in turn can result in the very least a return and a refund.

NOS parts are often the "holy grail" of the auto parts realm, especially if it's a part for which no or only poor reproductions are available. As such, they are often worth more than a reproduction part or a used part.

I have more than a few boxes full of main drive gears and output shafts for standard transmissions from the 1930s up through the 1960s.  Although most of the stuff is sorted by part number, the condition of individual parts varies from pristine NOS to completely worn out - all in the same box.  It's my job to sort them out.  There are a few cues I look for to tell me what I want to know.

The most obvious is the presence of a factory box.  But one must be careful, because unless the box is sealed from the factory, there is no guarantee that the part inside the box matches the part number printed on the outside of the box.  A lot can happen in 60 or 70 years, and it's not uncommon to find mismatched parts like that.  Often in the context of a dealer, whomever puts the different part in the box will have helpfully crossed out the old part number and written the new part number on the box, but again, this is still no guarantee that the part and the number match.

Often, a dealer in parts such as Little Dearborn will sort the used parts from the NOS or unused parts, because they sell them differently.  This is where an old archaeological concept called "provenance" comes into play.  Webster defines provenance as "the history of ownership of a valued object or work of art or literature".  In archaeology, it means essentially, what is the context in which the object was found.  This is important, because this context can often give us much more information than the object itself. It can tell us what objects are consistently associated with which places, or what objects are consistently associated with other objects, and so forth.  Without the context of the objects being recorded, this information can be lost.  Maintaining provenance is the biggest reason archaeologists conduct controlled excavations - each object is related in three dimensions to a common datum, allowing future researchers to essentially reconstruct the site virtually.

Yeah yea yeah, ok so what does this have to do with an input shaft for a 1950 4TH 4-speed transmission (part number 8MTH-7017, in case you were wondering)?  Well, if the parts are sorted, you want to maintain that sorted state, so that later you won't have to redo the work the original sorters did.  So, a complex explanation of a simple thing.  Well, that 's what we academic types are best at.  Have to justify our jobs somehow.

So what about using the cleanliness of a part as an indicator.  Well, sometimes.  If you have a pristine looking part in a pristine sealed box, it's pretty clearly NOS.  But what if you have a dirty part in a box?

The below picture is an output shaft for a 1949-1950 Ford passenger car with 3 speed standard transmission.  It is NOS, but it looks like absolute crap.  This is due to the deteriorating box shedding paper particles which then stick to the grease coating the factory used to protect the part from rust. Not pleasant, but at least it doesn't stink.  Just because it's dirty does not mean it's not NOS.

Sooooo, if it's clean, does THAT mean it's NOS?  Well, no.  Below are three main drive gears - the bottom is a 48-7017 (1932-1939 3-speed), center is a 74-7017 (1937-1940 3-speed used with the 60 hp flathead) and on the top is a C2OZ-7017-A2 (1962 Fairlane with 170 or 262 CID).  All are clean, so one must look for other clues.


One way is to look for wear on the gear teeth.  Examination of the teeth on the 48 gear indicates pretty extensive pitting.  This is not wear from use, but it pretty clearly was rusted enough at one point that pitting developed on the surface of the gears.  While this part might be usable if you're just throwing a transmission together to get a car to run, more often that not it's going to be useless in the context of an extensive restoration.  Also note that the part has some rust, and the bearing surfaces are discolored and worn.  Into the pile of parts used for art it goes.


By contrast, the 74-7017 looks a lot cleaner.  The bearing surfaces are bright and shiny, there is very little rust, and no pitting on the gear teeth.  However, close examination of the teeth shows a polished patch in the center (difficult to see on the picture) that indicates the part has been used.  It is by no means worn out, and can certainly be useful to a budget minded restorer, but is not NOS and would be sold for considerably less.


The top drive gear shown in the first picture is also clean, and does not show signs of wear on the splines or bearing surfaces.  Close examination of the gear teeth indicate striations, that I think are left over from the manufacturing process, present across the entire surface, indicating the gear has not been used with another gear and had a chance to break in and develop the polished patch. I would call this part NOS 



This is just one of many ways for determining condition of various parts.  The truth is, I clean parts like this regardless of the condition may be, because removing the gunk is essential in determining wear on the gear teeth.

until next time....

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