i was wondering what i would have to do for a drift car because of the tension rodswould i have to put in a silvia back end suspension or what/

advice appreciated

You are talking about two things here.

First Silvias and 720s are completely different vehicles built for two different purposes.

Secondly, suspension is not universal. And you can probably just drift your truck with little help.

To lower the center of gravity, (Front)Drop spindles or lowering your truck with torsion bars, rear you can try to take points from mini truckers welding in your own multilink or drop the rear on blocks.

Check out the last post in the 720 picture thread and look at the rear set-up.

I slid my hardbody every weekend at local events.

You can get spindles for the front, with ford pinto shocks.

3" leafs for the rear with a 2" block, and redrill the hangers

And then get a locker or weld your diff, you have no need to modify the steering parts to drift.