Depending on your production, they might have some reasonable terms.
Here is their 50's Era Sampler for download. It's mostly radio ID stuff, but perhaps if you called them they could tell you if they have product jingles as well.
Thanks guys! I found a file on Sounddogs that would work great but the price is 90+USD! That would be great if that was in the budget. This is actually going to be used as part of a prank. I will keep looking. Thanks for the PAM and prelinger links as well- I will look a little closer at those.
Would it be worth a call to Unilever or Chuch & Dwright. http://en.wikipedia.org/wiki/Pepsodent? They may have some audio files that they would be happy to give you with rights.
I emailed Church & Dwright. I will see what comes of it. I also found a forum where people do voicover/jingle work and I have inquired there if anyone would be interested in helping to make a jingle. I also found a UK site where a guy does radio jingles but they all are sound fx laden with a deep voice. I also sent him an email asking if he is capable/able of doing what I want.