Read what I posted in the original post: "1142 bulbs".
I didn't pull that number out of thin air.
That's from the bulb I pulled out of the back up light socket.
If this type of bulb was only used up to 69, then your resources are wrong.
You might want to try another website.
It's off of an original unmolested 1970.
I didn't ask for info on 1157 bulbs or the history of the bayonette style automotive bulb either.
I needed info from a knowledgable source on a 1142 backup bulb for a 70 mustang, any monkey can do a Google search.
I know what bulb I need, just don't know why Barney Fife at Napa was trying to give me something different.
Hopefully someone with a similar issue with this bulb will respond, and not someone trying to build up their posting rating