One of these is a #2532 plug from a rear axle housing. The other is the #3080 plug from my touring's oil pan. They seem to interchange perfectly. The fiber gasket fits them both. I wonder why Ford bothered to maintain separate inventories of the same part under different numbers.
Steve I don't know about the difference. I throw all of them away and install model A plugs they are twice as thick and not as susceptible to stripping the outside comers.
Just to confuse us? Or give us something to talk about in latter years? How knows for sure.
My brain is not working too good, I am visualizing your car with spark plugs in the tranny and diff.
Clearly they are meant to handle different types of oil. (lol j/k)
nah...the 2532 for the pumpkin original with the screw slot was meant to be indexed top to bottom vertically...the 3080 for the oil pan originally with the screw slot also was meant to be indexed sideways from pan ear to pan ear! So they needed two drawings showing the orientation! (Just joshing)
They couldn't keep them straight and stock got mixed...and then they debated endlessly without reason as to why each was each and what individual purpose each served, just like we do today. Unlike today, they decided to compromise come the 1927 and changed the rear plug to be 1/2 pipe thread with a square socket head and marked the other 'use existing stock' (that fits)
I only imagine that the original drawings were both 3/4-24 but with completely different heads and perhaps completely different thread leads, or a groove machined under the head of one and not the other...but would need a trip to BFM to know for sure.
To complicate matters further...For you over restorers, I have yet to find a gasket for the 2532 version but wouldn't put one of my cars together without one
The responses indicate it is really more of a joke than an actual question.
But an actual answer to the original question would be: Henry Ford tended to be a frugal businessman. And you are correct that maintaining two different inventories for the same part would not make good business sense in most cases.
In this case both parts have the same "factory number" which was 817. And it was used for both part number 2532 Diff housing oil plug used 1909-1926 as well part number 3080 Crank case drain cup plug. In the case of the 3080 part number, it states “Order 2532” so the person looking for the part knows which part number to actually order. And when it changed from the slotted to the hex the “factory drawing” would have most likely been updated first and then the new part ordered and/or made to the updated drawing specifications. We know that it was not considered a major change to the part because the part number did not have a suffix added to it – nor did the factory drawing. You can use either style plug – they fit and function fine. Note when Ford changed to the 1/2 inch pipe threaded plug for the rear axle it was a significant enough change to warrant a suffix on the part number – which became 2432B and had a new “factory drawing” number of 2824 that in the Aug 5, 1928 Price List of Parts for the Model T was updated to the A24457 which was the “factory drawing” number for the same part that was used on the Model A Ford. And it is for use in the rear axle housings that were threaded for the pipe plug.
Note, both the slotted and hex plugs had 24 threads per inch (TPI). I’m not sure what the 1/2 pipe plug had for threads per inch in 1927 but from the chart at: http://www.engineeringtoolbox.com/npt-national-pipe-taper-threads-d_750.html they list 14 threads per inch for today’s pipe threads. Based on the difference in thread per inch, I would recommend using the correct plug on the rear axle or engine pan if the threads are still good 24 TPI. Of course I always learn new things here – and perhaps the 1/2 pipe thread was close enough in threads per inch that it does not harm the original female threads. But I suspect it does. If someone can confirm that – please let us know.
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