1975 Ford E100 backup light switch location

[dfhunter2000]

I just recently purchased a 1975 E100 van and I'm trying to find the location of the backup light switch. I bought some Ford shop manuals and they stated it should be on the steering column. This is not the case. There are however two wires that go down towards the transmission that could possibly be a Neutral safety switch but I haven't looked further than the steering column yet. I was wanting to know if anyone has information on where it could be since it isn't on the column?

Thanks.

I'm not sure of the transmission type other than it's an automatic, but it does have a 351, and the transmission does not have overdrive if that helps any.