These were the years when CBS was becoming fully integrated as the managing element for functional day to day operations. From mid '65 through the later 60's, I could imagine things remained somewhat consistent as they were probably using pre-sale stock etc. According to 'The Fender Bass' An Illustrated History - the threaded saddle bridge was used until 1969 - so your single slot saddle bridge could have been swapped for the original. For whatever reason, this was common back then. The single slot saddle version was used from 1969 (mid year) well into the 80's. The base plate was beefed up in '82 thru '85 - perhaps yours is one of those as they did a lot of strange things during those years. The pg is definitely from that late 60's period as it has the skinny black center layer - it's just in very good condition. Pg's like this show up on eBay selling for hundreds of dollars.