Original 340 baseplate. You need to measure the throat height to tell if it is a 70 or 71 340 base.

4-Barrel Shaker Bases

Engine--Part#--Throat Depth*

1970 340--3512765--1 ¾”
1971 340--3512764--1 ½”
383--3462485--2”
440-4--3462484--1 ½”

* Measured from bottom the carb stud bridge to the bottom of throat base.