ROLL CAGE IS THERE A DIFFERENCE

Can anybody tell me if there is a difference in a roll cage for  a 68-69 amx to a 1970 javelin will it fit right??or is there a company that makes one spcifically for a1970 JAVELIN

how difficult is it to install?and what kind of rules does nhra have i think i heard the bar behind the seat has to be a certain hight is that true?

On a car like yours they supply 6"x6" steel plates that you weld to the floor first so the bars won't push through the floor pans. I didn't like that method so I added 2"x2" crossmembers under the floor to set the bars on. At the front footwell area I put a peice in from the factory frame rail accross to the rocker panel. At the main hoop I went with another crossmember all the way from each rocker panel and with a hump in the middle to clear the driveshaft. The rockers on a unibody car actually transfer the front frame rails to the rear frame rails and are structural members. There is a thick vertical plate sandwiched in the center of the rockers that is your frame. I also added 2x2 subframe conectors. Follow the NHRA rule book but you still need to know your car body and attach the bars where they will actually work. You can buy a prefabbed cage kit but many backyard guys have the tubing benders to make there own cages. A buddy of mine makes custom cages at his house, but he needs the car to fit it. He doesn't have a cad setup and jest bends patterns out of 1/2" EMT.

Anyone use both S&W and Chassis Engineering cages? Just wondered who had the best quality cage.