I found the slide rule that belonged to my dad. He became an engineer in the 1950s. The internet has given me a lot of information about it.
It is a Keuffel and Esser ( K+E ) model number 4181-3. I found that was a plastic Log Log Duplex Decitrig. It must be from before 1962 when Keuffel and Esser changed all their model numbers. It is Made in U.S.A. - all plastic (trade name "Ivorite") stock, plastic cursor lens.
There was some moisture in the case at some point. The thin metal bands around the cursor rusted. It all still slides. In the 1959 Price list it had a retail price of $15.00
I have the manual. It is in pretty good shape. That might be the more valuable part The manual is 4081, which must have been the metal version. That was $22. You can download scans of the 4081 manual here. http://sliderule.ozmanor.com/man/man-download.html