Tom Overfield and I corresponded thus:

> The 75 was advertised as a 1964. I'm not sure if it really is or someone
> just looked at the date when it first was produced. Of course it would be
> great if it was an early one.

That's only from the "older is better" point of view. The ones from the
first few years had flat-top clip-screws and tassies and a longer clip and
I believe these parts were made of a heavier metal (solid brass or bronze)
than after the change. The weights of my before/after specimen's are 21.5
and 17.9 grams; that's a significant difference. All that additional
weight was above the pen's balance point when the cap was "piggy-backed"
for writing and those early 75's are noticeably top-heavy whereas after
the slight change, they were much more well-balanced.

Allan Tischler sent the following:

There were 9 different Sheaffer PFMs produced from 1959 through 1963. They are categorized as follows:

PFM I: plastic cap and barrel, chrome trim, Pd-Ag nib.
PFM II: brushed steel cap, plastic barrel, Pd-Ag nib.
PFM III: plastic cap and barrel, GFT, 14 KT nib.
PFM IV: steel cap, plastic barrel, GFT, 14 KT nib.
PFM V: GF-cap, plastic barrel, 14 KT nib.
PFM VI: GF-cap and barrel, 14 KT nib.
PFM VII: 14 KT cap, plastic barrel, 14 KT nib.
PFM VIII: 14 KT cap, barrel and nib (a.k.a "Masterpiece").

In addition there is a PFM "Autograpgh", which has a plastic cap and barrel, 14 KT trim and nib.

Peter Wichert posted some of this and corresponded the rest to me privately:

Aero fillers were dated through 1951--those made in the '50's have a 2-digit date stamp in the same place as the vac models. Strangely, 51 pencils were dated through 1953. Other distinguishing areo model dates: "Made in USA" added to cap in 1954, Superchrome ink dropped from filling instructions in 1957, Parker arrow logo added to cap in 1958, barrel breather hole moved to side of pen in late 1960's.

> Me again. Do you know when they shortened the clip on the aeros? I have
> several from '50 with long clips and a couple (which seem to be original
> barrel/cap combos) from '51 with short clips. Does that sound about right?

Yes it does--the clip was shortened in 1950 (but perhaps it took them a while to work through the old inventory) when the aerometric was "improved". The key to look for on an improved model is the number of pressings called for on the instructions on the filler sleeve. First edition aeros call for 6 while improved call for four. This si because the guage of the breather tube was increased. Other "improvements" include an o-ring under the hood at the cap clutch ring and a lip on the inside of the barrel--i.e., the threads do not extend all the way to the end of the barrel on the newer models. Plum color was also dropped at this point.

> Also, do you know whether there was any interruption in the 51's production?

51's were in continuous production only from the end of WWII to about 1951. At other times, they were made in batches--my contact at Parker told me they only made one batch (of about 20,000) in each of 1942, 3, and 4. The last batch was made in 1969/70 and lasted for about 8 years. I do not know how many were in that batch.

51s were made in England until 1981--they are virtually indistinguishable from the late US model, save for the fact they are convertible. (A US convertible model was made in the early/mid 1960's, but they are exceedingly rare.)

In an email to me, Allan Tischler wrote:

In a letter sent to me from the Corporate Secretary (unofficial historian), Tom Franz, he enclosed a copy of a page from Sheaffer's 1953 catalog that describes the nibs: "...Sheaffer's new and enduring palladium-silver point, a costly combination of precious palladium, sterling and 14K gold." He went on to say that this nib was introduced in the Snorkel line during its introductory year, 1952 and continued at least through the 1950's. He believes that it continued into the early 1960's as well, but was unable to confirm this. Therefore it is probably safe to assume that all 1-tone nibs produced through the early sixties are in fact this precious metal alloy.

Tom Overfield forwarded the following clip from Lambrou's book (with apologies for his typos):

Sheaffer celebrated its 50th anniversary in 1963 with the introduction of a new updated line of liftime pens, the first since 1947 to carry a guarantee for life. The new pen, in a style later called Imperial, was cartridge filled and became very sucessful. It was fitted with the inlaid nib. Although the aniversary lifetime line was discontinued in 1969, the Imperial style was contiued and over the years had been marketed in a wide range of designs and finishes....