Ford parts catalog doesn't go into a lot of detail or specify what the qualifiers were for vehicle applications. The shield is a 70-71 Torino sourced part. DOOZ-10A682-A was listed for 70-71 Torino and 1970/ Mustang. Applications on earlier pre 70 cars were mostly Big Block and AC cars. My 70 Torino GT "M" with AC and 24 series battery did not have one. Both of my 71 "M", AC, 24 series battery Mach 1's didn't have the shield. I had three Gran Torino Sports, (two "Q" and one 429) with the 429, AC and 27 series battery vehicle as the only one that had the battery shield. As stated above a lot of them were tossed when the battery was replaced. Some were broken or warped from under hood heat and the customer felt it was easier to throw away than to replace.
There was a alternator splash shield listed for the 250 6 cyl and 429 (D1OZ-10317-A) before 5/1/71. After 5/1/71 there was one listed for the 250 6cyl only (D1ZZ-10317-A) that continued through 1973.
Pastel Blue's comment on production line variances made me think of an interview with an assembly line worked Boss1Ray posted. As the car approached his station to have the seat belts installed he noticed a freshly lit joint in the ashtray. So I guess it depended on how much of the joint was left as to how much attention your car received at each station! :whistling: