Help decoding this bell housing !

According to Brewer's website, that's for '69-'71 A body and '70-'71 E body; fits transmissions with the 4.354 bearing retainer.
They also offer conversion torque shafts and linkage to use the 10.5" bell in '63-'66 A bodies. You *may* have to flatten the pinch weld in the tunnel for bellhousing clearance.