I am replacing the brake and fuel lines for the '72 Chevelle. As of right now, we will be unable to lift the body from the frame to get them back in. These are pre-bent stainless steel lines.

I have been cursing and "flicking-off" these lines trying to get them back in. Any ideas? Can they be cut and fastened with a rubber hose to get around the rear hump? What would be the drawbacks of doing this?

There has to be a trick to these?

this is what I did on my 70. I cut them right before the rear axle and flared the ends.
http://www.chevelles.com/showroom/data/500/medium/000_0381.JPG

It isn't that difficult to lift the body from the frame to put in a new fuel line. I just did it on my 64 Camino and I was only working in a one-car garage and it was the first time I ever did it. Put the car on four jackstands to let the suspension hang free, otherwise the frame will lift with the body. You only need to loosen all of the body mounts bolts on one side of the car and remove all of them on the other side and lift the body about 4-6" inches off the frame with a floor jack and block of wood, and then put support blocks under the body. That is, if you can loosen/remove the body bushing mount bolts with breaking or spinning the cage nuts. Mine were all new so I was in luck; if they're rusty be careful. Also, had to remove the bumpers and disconnect a few other things. I also went with the pre-bent stainless steel line. It took some effort to massage the line through the hole in the front of the frame to the engine. If all the pre-bent lines are like mine, they aren't exact but pretty close in the bends and fit. One man can do it carefully taking his time, but get a helper if you can.

It will be impossible to put in the lines without cutting them and flaring them unless you lift the body. Stainless steel is hard to flare; you'll need to have a good expensive flaring tool or have a shop flare it for you. You could also use a braided stainless steel hose and hard-tube adapter fittings if you want to cut the line in two in that spot.

I definitely wouldn't cut them to use a rubber hose over the rear axle/spring, there's a reason GM didn't use rubber there; the way he did it in the pic is probably OK. I prefered to have a solid line running all way without putting in any fittings that may eventually be a source for leaks.

We have been hesitant in lifting the body from the frame due to the nuts and bolts holding the two together spinning when we attempt to unscrew them. If the nuts spin when we are going to have to do some cutting into floor board and truck to fix the problem. This is something we would like to avoid.