according to my peterson's pinto book, cats started on pintos in 75. That doesn't mean they all got them though. I think it depended on the area of the country or states. I know up until 79 trucks and vans didn't have to have them. We had an old 78 econoline that had non-catalyst on the valvecover. If you still have the sticker on your valvecover, check that and see if it says catalyst or not. If not show it to the DMV guy. If it does, you'll have to run one.
-Harry