Complete Trunk Floor... HELP

[Firebird-Geek]

I am placing my first “major” panel… “complete trunk floor” (AMD). First time doing this! So I hope to get some advice!
https://lh4.googleusercontent.com/-t6mC5SzXfAQ/TtQGaB6TclI/AAAAAAAAASw/JXZXuNTa54M/s640/Rear%25252010-10-11%252520%252528Large%252529.JPG
https://lh4.googleusercontent.com/-J8aJOHN3oxI/TtQF5M0__HI/AAAAAAAAASo/rL6sx48Fr8c/s640/IMG_1820%252520%252528Large%252529.JPG

As you can see I have taken the car down pretty far in the battle against rust… and am finally getting ready to put parts back on!! (exciting time):D

With so much of the car gone, I find it a challenge to find places to measure from to make sure everything is true and square with the rest of the car.

What I came up with was:
Clamp 1” square tubing to the back of the trunk pan… (where the tail panel will be attaching) and then using this bar to measure from the front of the quarter panels (right in the middle of the door opening and back to the front of the 1” square tubing. I figured this way I know the trunk is squared up as far as the quarter panels are concerned. Right now it sits 65 1/8” inches back from the front quarter panel lip by the door opening.
https://lh5.googleusercontent.com/-qJX3yhukHsY/TtQFSc5nXCI/AAAAAAAAASA/t6uqlJKDNpU/s640/IMG_1832%252520%252528Large%252529.JPG
https://lh5.googleusercontent.com/-seudPHCanS8/TtQFScnTDyI/AAAAAAAAASM/r-FLv1EH5_o/s640/IMG_1833%252520%252528Large%252529.JPG
https://lh5.googleusercontent.com/-Mf3N__Tap70/TtQFpasbYUI/AAAAAAAAASg/-n-jnnn30q8/s640/IMG_1825%252520%252528Large%252529.JPG
https://lh6.googleusercontent.com/-qQqWd2wR-x4/TtQFShhX-cI/AAAAAAAAASI/VZn5SHTigyQ/s640/measurement1%252520%252528Large%252529.jpg
https://lh6.googleusercontent.com/-GcDEb3fva_c/TtQFTLJ156I/AAAAAAAAASY/S84kAgTsG3I/s640/measurement2%252520%252528Large%252529.jpg

I do have the original inner rear panel in place, but it doesn’t seem to help locate the exact placement of the truck for I can push or pull it in or out a good 1/4 inch also… I did take pictures of the "overhang" of the trunk floor to this panel... but not measurements:( (BEFORE PICS)
https://lh5.googleusercontent.com/-U7JSOP4-amU/TtAf4nXOCkI/AAAAAAAAARE/dsbENQg6zY8/s640/IMG_1646%252520%252528Large%252529.JPG
https://lh6.googleusercontent.com/-pmauZfCzdC0/TtAf4tPTzRI/AAAAAAAAARI/fPaYKChR3fo/s640/IMG_1645%252520%252528Large%252529.JPG

I can not test fit the quarter panels right now for if you look at the top of the old quarter panel area, you will see a bit of it still there… it is holding the rear internal bracing from sagging all the way down. Without the inner wheelhousings in place... it is a bit flimsy.

QUESTION: How far forward or backward should I have the trunk floor sit?? I can move it forward or backward a good ½ inch. I don’t want to get it to far either way... figuring it will mess up the tail panel fit, quarter panel fit, trunk lid... and almost everything else… So now I have the “Fear before the welding” setting in… is there some room to play, or do I need to get this EXACT? Is there somewhere else I can measure to get exact placement?

Any advice is welcome… I don’t want to start off with a bad foundation….

[DOOM]

If the floor sits in the contour of the rail you should be fine. If I'm understanding you correctly. Are your rails all locked in?

[Firebird_67]

yes frame rails are in original location... my fear is that if I have the trunk pan a bit to far back,the tail panel will be to far back and may not meet up with the quart panels at the rear. Or if I place the trunk pan too far forward, the tail panel may sit too far in, and again not meet up with the quarters correctly.

Or is there enough "free play" there from GM that it only needs to be close? Am I looking for an exact location or just close? Not sure how much flex is in the tail panel?

[DOOM]

In this situation shorter would be better.. Split the 1/2 inch difference and weld it in. The measurements on these cars are all over the place.. When I took my car apart I measured everthing,I was getting as much as 1/2 inch differences from side to side! These cars are no where near the 3mm tolerences that the cars have today. They used alot of shims in those days to get them ''CLOSE''.....

Also DON'T measure a aftermarket piece thinking its the same as the OEM! I learned this lesson the hard way. These aftermarket parts are like finger prints there all different.. If you need anymore help give me a call 708-430-4411 Mario