What Trac Bar for lowered rear end

[Frankie P.]

Good afternoon to you all,
I'm in the process of lowering the rear of my 71 SWB with coils. I've got 4" springs and 1.5" blocks. Question is, do I need a new trac bar? An adjustable one? And if I do need one, do I need just the adjustable bar for stock location or do I need the trac bar that goes from frame to the passenger side trail arm (ECE super trac type)?

Your help will be greatly appreciated
Thank you