Washer Bottles

[BigSig 6 Barrel]

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How do you tell a 1970 washer bottle from a 71 bottle.
I did some searching and found discussion on electric pump bottles versus the manual pump, but nothing on the differences between the two years/styles

Are the originals date coded?

Thanx

[Floyd]

70 washer bottles had a square corner and at some point later in the 70 production run they switched to a bottle with a rounded corner.  71 E-bodies came with the rounded corner but I'm fuzzy on when the bottles changed again for 72-later E-bodies.  If you look at original rounded corner bottles you can see that a pretty crude modification was made to the tooling that produced the rounded corner.  As for when the change occurred, I don't have any documentation but I have noticed multiple Trans Am survivor cars with the rounded corner, so maybe it was done in the March-April 70 timeframe.  I asked Frank Badalson about the Trans Am cars and all the examples he documented with rounded corners were the manual pump versions.  I'll try to post some pictures later.

I've seen some over the counter NOS bottles with ink stamped date codes but can't comment on OE bottleSs.

[mtull]

The early 1970 washer reservoir's with electric pump have a flat face on the side facing the radiator support whereas the later 1970~1971 have an indentation the size of a golf ball is my understanding. 
Example: later 1970 ~ 1971 E Body
Example: later 1970 ~ 1971 E Body
I'm not sure when the changeover in 1970 occurred nor how late into the 1971 model year the later style was retained.  Hopefully some of our forum experts will verify my assertion, I'm not 100% sure

[Floyd]

Pics of originals and one later NOS version.

[mtull]

Pics of originals and one later NOS version.

WOW!  I didn't realize they were that different.  Thanks for sharing the pics.

[BigSig 6 Barrel]

  
Thanks a Bunch for taking the time to help me Floyd & mtull

Based on your "Trans Am survivor cars" comments, that really helps narrow the time frame down for me .... and the photos were awesome!
Mine is a early April built car, so think I'll probably go with the later style bottle.

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[blown motor]

So my curious mind has to wonder why they changed the design. Was there an issue with the original design? Did they change something else which required a change to the washer bottle?    This stuff fascinates me for some strange reason.

[Floyd]

I suspect there was a problem with the square corner, either difficulty getting a consistent thickness during manufacturing, or too many warranty issues resulting from cracked corners.