1970 Big Block Alternator Bracket question

[Mr. Chevy]

I have seen two types of 1970 Chevy big block alternator brackets. One has the smaller, perfectly round hole on the topside face under where the negative battery cable bolts and the other has more of an oval or oblong style hole in it. Were there 2 types or is the oval/oblong holed one a GM replacement??? I was just curious....

Thanks Rich

[JRSully]

The pefectly round hole is the correct assmebly line bracket for a 70 BB. The round hole is where you would "jam in a screwdriver" to push up on the alternator to tighten the belt while tightening the alt.

[Mr. Chevy]

Thanks!!

Rich

[YENKO DEUCE REGISTRY]

I believe the oblong version started in '71'ish or was for the a/c cars - not totally sure.

[RPOL88]

1969 no hole. 2 small holes for battery cable and alternator wires. 1970 round hole with 3 small holes for same. 1971 and up oblong hole.

[Mr70]

For 1969,I think the two small holes were for the heater hose collar & alternator harness.
For 1970,the third hole was designated for the battery ground cable,but early assembled vehicles didn't take advantage of it as assemblers continued to ground them at the head for awhile still.

[JRSully]

The 3 holes on the 70 bracket represent ground, alternator harness hook in and bolt hole for heater hose bracket/clamp

[CamarosRus]

While on the 70 Alt Brkt subject......how do you recognize the small block alt brkt, and what asst of holes does it have ?????

Thanks,