I found the 5044401 on a Pontiac web site as 1960 & 1961 P8. I also found it in my 2/1/85 GM price book and it fits all car lines including Chevy and GMC truck. I have posted a link to the Pontiac web site part number search. How much for the speakers??
http://performanceyears.com/sp/index.php?Act=Part
Brian