what do I need to make the ls1 rear calipers work on lt1
 

The lines are different apparently, who has a kit to adapt the rear ls1 calipers to fit on the factory lt1 brake line? need to know this asap please!

anyone?

You need the entire LS1 backing plate. The LT1 car incorporate the emergency brake into the caliper. The LS1 style uses a "drum brake" style emergency brake.

I put LT1 brake calipers on my LS1 car and it screwed in just fine.

There really isn't much to be gained performane wise from the switch, the lt1 rears are pretty good as is. From what I've read about them it's quite a pita to make the switch as well. Only reason I could see to do it is for visual, the ls1's have a slightly larger rotor. I'm switching to LS1 fronts now but didn't see a reason to do rears.

The car has ls1 swapped brakes already and I was wondering if the brake line will just screw in the original brake lines leading to the rear calipers or not?