I put an A body A833 in my 87 Diplomat. Used the pedal assembly and tunnel out of an F body. Other than the firewall no longer having the hole for the clutch linkage already stamped out it pretty much bolted in. I used the donor F body to make a template to locate that hole. Kept the original driveshaft. Forget if I had to swap out the yoke though.

The FMJ bodies went thru some revisions over the years. Back when I was fooling with my 87 the yards were loaded with M bodies, the later stuff was a sight better than the early stuff so, by the time my 87 rolled out it had all the updates. I did add a bunch of cop spec goodies my civilian M body didn't come with. Added coolers, thicker sway bars and rear springs. Throttle knob, put in a AM/FM/CD player out of a Neon, Got the dual speaker dash top out of a 5th Ave. Put in the late B body 11.75 discs adn added the cop 8 1/4 rear axle with the cop 11" drums and a 2.94SG.

Put in a mild 360, 4bbl 340 cam, MP ignition.

Probably did other stuff, but I forget anymore, it's been close to 20 years since I sold it.