3%, it could be true, especially on an older horn, if all the solder joints that might be present were counted,(the solder has a lot more than 3% lead in.)
A Modern 2xxxx series brass body should be largely lead free. Lead is only really added to brass to help machinability and cutting performance in 3xxxx series alloys. Older saxes might not have been subject to the same rigorous production standards. Alloy production has become a lot more scientific, and metallurgists have a lot more control over the elemental makeup of alloys then there ever was in the 20s and 30s, so I would guess that the brass used for some of the classic horns was a lot "dirtier", and also varied from lot to lot by far more than modern production techniques would allow. Still, no one ever admits to having one of the many lousy mk VIs made, do they

Anyway, dont go eating your sax. As long as you blow and dont suck you will be safe
Under the European "RoHS" legislation, Brass has been granted an exemption from the requirement for lead reduction, allowing it to retain up to 4% Pb, so it seems unlikely that its "illegal" to produce modern brass with the same lead levels. Generally though a free cutting brass with lead would only be specified if it was going to be machined, which doesnt really apply to the sheet pressing of a sax body.
True "Red brass" is in fact a gunmetal containing a much higher copper content as well as Tin. Yellow brass is simply a regular 33% Cu / Zn alpha brass alloy. Its the additional copper content in Red Zinc that changes the colour, nothing to do with lead.
Sorry for the science content
