First welcome to the site hope you find it useful in your related endeavours.
Can't seem to find any U's with a generator. Might providing when and where your car was suppose to be assembled?
On the early 6 cylinder generator Mustangs I recall no rubber and metal shield on anything but the V8's and on the 6 cylinder a simple rubber boot covering the rear couple of inches as shown in the picture below
If I were looking for these I would first check with the Falcon sites, shops and parts guys

Again welcome to the site - sure all of the early 6 cylinder guys will be along any moment

**mod edit... change 'T' to 'U' :-) **