they had to do a lot modification to make it work. they used a TCP power rack.
the problem with doing a rack conversion on the big body cars is that the stock PS system actually performs pretty well on those cars since it doesn't have the hang on bendix style power ram assist but rather and integral power gear box. there are a bunch of places that can modify that gearbox with better ratios and internal parts, etc. IMHO, there just isn't as much of a need for a rack conversion on the big body cars given that they already have a decent setup to begin with. personally, i would investigate ways to make your stock gear box better.