They are in the R/R passenger area floorboard area, if not through the floorboard, on the mustangs, they are through the rear seat wall at the floorboard. ( Fender well area. )
The RED restraint strap clipped to the eye bolt, I used it several times in Stockton. I can not remember the year, but they started putting them in the cars when they introduced the restraint strap. There was also a BLUE restraint strap that laid on the floorboard, usually R/R.
It was used for hog tying, leg restraint etc. It worked well also. It was not clipped to the eye bolt.
The earlier cars did not have this. I came on 1-83, seems it was the later 80's they started the eye bolt and straps. I can not remember the exact year. I know all of the mustangs had this once they started using them.
That is one thing they sometimes forgot to remove, if they did remove it, the hole is usually easy to find. A good look under the car floorboard, or R/R inside fender well I believe.
The red strap clipped to the eye bolt, then went in between the R/Front seat cushion and backrest. It was then clipped to the chain on the handcuffs. Tightened at the floorboard and kept the prisoner's hands and cuffs tight up against the seat back rest.
Worked good for a combative prisoner.
On the paper bag...... I never used that method wish I would have lol but I do know that there is never any noticeable evidence when using the back of ones fingers on someone's face in the R/F seat.
This usually worked real well for spitters or mouthy individuals
