Some of this has already been posted but here is my summary on the 1931 Slant window 160A, B, C
As far as Murray or Briggs, when Ford built the 31 Slant Window he had Murray and Briggs build the bodies the same so parts were interchangeable. There are some telltale differences such as Briggs used d-nuts on the fire wall and Murray used caged nuts on the firewall. Also the Briggs had a manufactures mark the Briggs “Bug” on the lower front cowl see photo below.
The 160A. The ford Standard town Sedan had scrolled door and window handles, painted molding around the windows and painted front dash; the dome light was centered in the car with a switch on the light and a rubber mat in the driver's compartment.
160B. The ford deluxe town Sedan had a pull rope on the back of the front seat, simple non scrolled door and window handles, wood grained molding (with a scalloped lower frame ) wood grained front dash, the dome light was over the back window and was controlled by a sliding switch on the door post, cowl lights and carpet.
160C. same as 160B but no rear quarter windows, referred to as a blind back.
Slant windows had flat firewalls until the indented firewall started in April 1931.
Photo of the Briggs "bug"