[fleetsidelarry]

Slammed, removing both riveted braces gives around 32", allowing for say 1" clearance behind the track bar. on my '66 the driver's side of the front brace is where the bracket for the track bar also mounts, but your '63 may be a little different. that corner might take away a couple of inches if you're keeping the track bar.

removing just the back brace gives about 28" because of the way the front brace angles back on the passenger side.

these measurements are rough since I don't have the rear cross sill on and I wanted to error on the side of giving you clearance.