The only difference is the location of the bellhousing side arm. The 1970 up E body big block(and 71-74 B body) uses a straight adjusting rod because the arm is closer to the end of the tube, and the adjusting rod goes straight to the clutch fork. The small block version (same as 1966-70 B-body) uses an adjusting rod with a 15 degree angle in it, as the arm is moved further in from the end of the tube, and the adjusting rod has to run at a slight angle to the clutch fork. The small block torque shaft/adjusting rod will work on a big block. The big block E-body torque shaft/adjusting rod will only work with the 10.5" bellhousing, not an 11" or Lakewood.

Wayne