Believe it or not, when I took the L bumper off of my '74, there were no big holes for the bumper shocks (or any bumper shocks)! There were only 3 small holes on each side where the bumper bolted to the car. There were also indentations for the signal lights.
This is not the first L that I've seen this way. We've all heard the stories of deTomaso making bodies, then not completing them 'til years later. I'm guessing that mine was one such car. If you have a late chassis number, you probably have the holes and shocks.
There is an easy way to tell which you have. Using a small flathead screwdriver, gently pry off one of the round caps at the end of the bumper. If you see a nut there, I'd bet it's bolted to the shock that's passing through a big hole and bolted to your frame.
If you want to physically verify it's there, turn the ignition key forward to the 'run' position. Flip the headlight switch on to raise them up. When they're about halfway up, turn the ignition key all the way back to the 'off' position (this will stop them in their tracks). Take a flashlight and look into the headlight bucket opening toward the bumper and radiator. It would be close to the top of the fender, so you may have to stick your hand in there and feel for it. Move the headlights up and down a bit using the ignition key and headlight switch for better access. If you find you need to remove the headlight, do not touch the two screws for the headlight adjustment. There are only two per side, and they're 90 degrees apart, top and side.
The above paragraph also describes the procedure for removing the bumper shock when it comes time to remove it. You can probably also remove it by taking off the forward splash shield in the front wheelwell and raising the headlight all the way up. I didn't have any to take out, so I don't know which way would be easier.