Stumped...what are these for?

After getting my car up on a rotisserie this past weekend, I found something that has me stumped. I bought the car as a basket case essentially with many parts removed and not marked very well. The victim is a 71 Dart, 318 car. What I found were two bolts screwed into threaded holes on the bottom side of the driver's side front frame rail. The bolts in question are both positioned in between the two bolts that hold the K-frame to the rails. There are not any holes in a similar location on the passenger side of the car. I cannot figure out what these bolts are there for. ](*,) Can anyone help me out here? Thanks. L8r

Jim