I did find a similar one with a gold bezel and gold center links on the bracelet that had the same dial and date magnifier. This second one had all the papers etc. So, I guess they do exist.

try here: i778.photobucket.com/albums/yy65/joeiwc2014/1_zps3cc69712.jpg

Hi.
Thanks for follwoing up and I'm sorry about the wait. I've been travelling for work. here is a photo from google. This is not mine. If the owner or the site wants it to be taken down, please go ahead and do so.

/home/joebeamax/Desktop/2.JPG

Not sure if I can post photos. It's on a seller's website.

Hi Thomas,

Thank you very much. I did indeed already see that one with about 6 or 7 different other queries in the archive, but none of them really got at the heart of what I'm asking, which is: was there a transition period between the 3506 and 3521 when both were on the market? Did they share any similar traits? Or was there a model in between the two?

The model I'm looking at has a dial that seems halfway between the 3506 from the 1980's (very heavily checkered) and the 3521 from the late 1990's (white). It is white and finely checkered. It also has a date magnifier, but the wording and lettering on the dial is very much like the SL from the 1980's...

Has anyone ever come across a model such as this?

Hello Everyone,

This is my first time on such a brand specific forum as I usually participate in more generic watch forums, so kudos to IWC for drawing me in! It must be something about the design...I almost took the plunge on a cal 89 from the 1950's, but thought I'd get acquinted with a more modern piece first.

Anyways, I've tried to read as much information as I can about the 3506 and have read some of the Ingenieur model charts posted in the archive here, but I can't really get my head around the entire range, especially in the 1990's as the information is cloudy in parts.
I'm interested in a model which the seller says is from 1997, is that even possible? I was under the impression that the Ingenieur Automatic SL was out of production by the early 1990's. Did they sell them at the same time when they were selling the model ref. 3521?
The other thing that is strange is that the glass has a date magnifier, just like the 3521, but the dial is clearly more like a 3506 ( a little less checkered, but there is a pattern on the dial).
Was there a crossover period in which the two models shared some parts?

Thank you so much for your time.