Greetings all. Im new to the sight. Im looking for technical information on Frame of a 71. I have the typical diagram with a few of the general specs. What im looking for is specifics like cross measurements for the front horn extensions I sure this car has been hit a time or two. It was a complete basket case. I have it down to the frame and I want to ensure that its straight before I do anything else. Some of the body mounting bracketry looks tweaked. Im looking for a way to determine what is straight and whats bent. Nothing is major out of shape But I can tell from side to side that the front corner mounts are no longer mirror images, The bend is so slight that it wouldn't be noticeable without something to compare it to. any help pointing me in the right direction to ensure I have straight parts is appreciated. Thank you.

The A.I.M. for that year is a VERY Good place to start. 

Welcome to the forum. All I can offer is the Factory Service Manual has a few frame dimensions in it. You might check with a Chevrolet body shop to see if they can provide any assistance.

This is from my 72 factory service manual.  Should be the same.

Not sure what A.I.M is lol did a search and came up with nothing. can you enlighten me. thank you

This is the diagram I have. Perhaps Im getting in to the weeds? was thinking some thinking that measured out control arm mounting points compared to each other and trailing arm mounting points to ensure everything is where it belongs. but thank you!

The AIM is the factory work instructions on building the car.

I think if you measured the dimensions in the diagram and check the squareness of the frame by measuring diagonally to the body mounting points then you should have a pretty good idea of how straight the frame is.

SORRY my Friend.  "A" assembly, "I" instruction  "M" manual.  It has a multitude of information on getting your ride in correct shape. It does NOT tell you the sequence in which it is put together. 

Thank you, Gentlemen. I now know the frame is 1/2" to 1 " out of square. seems to be damaged just behind the driver's motor mount down to where it straightens out for the rockers. Its sad this is a number matching car, Frame, engine, and Birdcage all still together, trans and diff are marked correctly for the date. Not sure what to do, straighten the frame is beyond my ability. if it wasn't numbers matching, I would just get another frame, but I hate to do that on this. Any Ideas???? would even consider swapping project with some one more capable and wants numbers matching car. Suggestions welcome and thank you !

Since it sounds like you're down to a bare frame, I would think a body shop that has frame straightening capability could do that. Not sure how much it would cost however.

I guess you could  weigh the cost of straightening it versus the cost of a replacement frame.