Here is some background before I respond to your question.
Complete G-E model timelines are non-existent online; maybe a service manual would contain one, but I couldn't locate one of those either. The closest I came for Swivel-Tops were a post from former VL contributor Kenkart, who posted a list of the early models:
I should mention that the V11, P1, et cetera, are what were listed on the vacuum cleaners as "Cat. No" (category number) followed by the model number (C1, C2, and so forth).
So apparently, the C-18 was the last Swivel-Top mid-line model. However, there were also the power nozzle top-line (beginning with C-100 in 1963) and lowboy budget-line (beginning with the C-65 launched some time in the early- to mid-'60s) which may have also still been marketed through 1978 in the US.
Vacuumsinc.com lists the following bag description:
"These vac bags fit GE, Premier, Whirlwind and Everclean swivel top style canister vacuum clenaers.
GE C bags also fits GE vacuum models C-1 thru C-18, 815, V11C1, V11C10, V11C13 and V14C9"
According to an attached article I located G-E's Housewares Division phased out its vacuum cleaner production in April of 1972, and their plant was purchased by Premier Electric Company.
The Premier moniker had previously been associated with G-E as the attached 1961 Swivel-Top ad shows, but the branding was used from 1972 to 1978, when Black & Decker bought out Premier in the U.S. G-E Canada continued producing vacuum cleaners until the early 1980s according to Doug Smith.
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Now to your question ...
It would seem that your V11C11 is from the late 1960s or early 1970s; I'm guessing that the P1C13 is just a 1972 rebrand of G-E's V11C13 (taking for granted that the 'P' stands for 'Premier'); and the P1C15 and P1C18 would presumably have been made between 1973 and 1978.
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Photos (I was unable to locate ads for your particular models):
1. A page from the G-E Housewares Division brochure showing the C-12, C-13, and U-7 (late '60s or early '70s) posted by Compactelectra. The full brochure is on this thread: www.vacuumland.org/cgi-bi...
2. 1961 Apr 12 SPOKESMAN REVIEW - G-E Premier Swivel-Top and Easy Glamur Shampoo King
3. 1962 Apr 7 TOLEDO BLADE Premier Swivel-Top ad
4. 1973 Mar 18 CONNECTICUT SUNDAY HERALD - Premier Swivel-Top Model P5C16 ad
5. 1973 Mar 18 CONNECTICUT SUNDAY HERALD - Premier Swivel-Top Model P4U5 ad
6. 1977 Oct 15 THE HOUR Premier Swivel-Top and Shelton 5-Gallon Wet/Dry Vac ad
7. 1975 Oct 26 TIMES DAILY Premier Swivel-Top
8. 1972 June 28 YOUNGSTOWN VINDICATOR - Premier Electric Co. and G-E Plant news brief
Thank you once again for taking the time to answer my question. I really appreciate the time you took for it.
My canisters with the 'P' are all labeled General Electric, not Premier. My little V11C11 is an interesting model; it's small like a lowboy, but has a front blower with removable cover. It also has a deluxe bumper with the GE name on it, like the bigger cord reel models, and attachment clips that look like aluminum on the back. The switch is a step on style, on the bumper between the aluminum clips. The swivel top is an older style, different from the cord reel models but similar to the small 'Lowboy' models. I didn't get a hose or any attachments with it. All the ones I have with the P catalog letter are in two shades of green, all cord reel models with the plastic attachment caddy. 2 of them are deluxe models with the bag sensor light and a motor speed selector. I have seen, on ebay, a Premier identical to one of my high end models but for the name. Could Premier have produced canisters with the GE brand name on them?
You're welcome, Michael. Sorry for the delay in responding.
I appreciate the information you shared about your category numbers.
It's plausible that Premier could have retained the G-E name for a time. I was surprised that the two names were used in Swivel-Top ads of the 1960s; I had not heard of that beforehand.
You may want to consider starting a table or chart of various models that you have or see that may at one point show the relationships of category numbers and features. That's the only way to figure out those details without company literature.
I have done that with Electrolux and Eureka along with some Hoovers.