How to cut a Crown Vic. Remove dash and remove wiring from it, if you haven't done that yet stripping out the extra wiring.
Remove HVAC. This might be a good time to remove the body from frame. I left it on the frame myself, but it made cutting the frame more complicated. If you do pull the body, remove the master cylinder from the brake booster. Isn't it nice that Ford put flexible brake lines on the master cylinder! Note body bolt locations, some are different. Cut floor along rocker on the inside of the upright seam. Cut firewall just under the crosswise seam. Make firewall 54 inches wide. Note, you will have sliced down through where one of the major wire connectors goes through the firewall. I cut a hole through the side of the Mustang footwell under the cowl drain. If you do this make sure you waterproof it as the drain will surely corrode the connection quickly. Cut down thru the firewall to the floor beside the body mount bolts. Then cut over to the edge of the rocker (3 layers). This is hardest area to cut ! The front of body should be free.
Cut rear seat ( package tray support). Remove rear quarter panels to access inner structure and cut it out!
Cut rear package tray upright at the ends, quite low, as they interfere with Mustang structure around wheel wells.
Slice across the rear most flat portion of the trunk floor and also forward along the trunk drop area. I tried to leave these bits on the CV but they just got in the way later. Remove the whole body from floor. Leaving the firewall and rear package tray support attached to the floor. Once the body has been removed, it is a good time to shorten the frame as required for your body. 3.75 inches for a Cougar and 6.75 inches for a Mustang. Also cut off the rear section of frame in the trunk area. I shortened the trunk pan 12 inches, but if I do it again, I would take less out and tie the flat part around the upper rim of the trunk floor drop into the Mustang taillight panel/ bumper supports.
Soo..I got caught up in a summer full of fun racing the Mustang. I'd say it is getting faster but reality is my driving has gotten better. No, really! Lol! Now that we have both cars cut to pieces let's try putting them together! One difficulty I found was where to put the hoist pads and support the body while I dropped it in place. The pads hit the frame on the way down , so I had to get creative. The body went up and down about 6 times before I found all the interference points. Most I have outlined already. The rear package tray lining like it did amazed me! I had taken measurements from the front wheel centerline to the firewall and the rad support and knew that would work out good but the package tray was pure good Ford engineering! LMAO ( Dumb luck!)
As I stated early in the thread, some simple fender flares from a Mustang aftermarket supplier could be the only outward giveaway as to engineering beauty that lies beneath Classic Mustang skin. Also I have very wide rims on my car (18x9.5 up front) so narrower wheels will help as well. But to be realistic you will never be able to hide the tires under unaltered sheetmetal.