The switch from 1911 to 1911A1 happened six years before your dad was bornGood eye!
Yes, my 91-year-old dad is ret. U.S. Army (30 years active duty regular Army), and his military sidearm was an M1911A1--so, I know a tiny bit about them (though next to nothing, really, as I wrote above). But it wasn't until this thread have I thought about the differences between the (original) 1911 and the 1911A1. Imagine: A thread on Scubaboard!!
rx7diver
Original 1911s are pretty much collectors' items at this point. I doubt anyone is carrying one regularly. But it was worth a look as movie studios and prop houses have some oddball old firearms so you can't really assume anything.
This is fun. It's how I got started on the internet, answering questions on rec.guns in the mid-90s.