Is the redline number for a 1970 L34 tach - 5000? What is the part number on the back?

The L34 and LS5 had the same redline of 5500 RPM. I think I read that some Atlanta cars got a 5000 RPM redline tach. I don't know the part numbers.

What 70 chevelle came with a 5000 redline tach and gauge package?

Jim, The small block cars that were ordered with the U14 instument package would have received the 5000 redline tach. As stated above some of the Atlanta built big block cars also received the 5K tach for some reason.

Jim, As stated above some of the Atlanta built big block cars also received the 5K tach for some reason.

:yes:true

My Atlanta (April 1970) built car, has one in it:thumbsup:

Is the redline number for a 1970 L34 tach - 5000? What is the part number on the back?

The redline is 5500 for the tach and the part number is 6469985 for a 1970 L34 tach. LS5 Atlanta 5000 rpm tach cars were a different story, of course.

What's in box 72 of the build sheet?

Here's a brief summary of 1970 Chevelle SS Tach's. Ultimately, you must look at the car's original build sheet to verify which tach came in the car (not all SS Chevelles came with a tach but all SS Chevelles had the round dash pods). You begin by looking at box 107 of the build sheet to see if the car came with the U14 IP Gauges option. If it does have the U14 IP Gauges option, then your next step is to look at box 72 to see the code for the tach in your car (if your car does not have the U14 IP Gauges, then you will have --- in box 72 which means no tach). Ok, now after looking at the code in box 72, here is the breakdown of the tachs that most likely came in the 1970 SS Chevelles:

L34 396/350 hp 5500 rpm tach code 985
L78 396/375 hp 6500 rpm tach code 983
LS5 454/360 hp 5000 rpm tach code 938 ****or****
LS5 454/360 hp 5500 rpm tach code 985
LS6 454/450 hp 6500 rpm tach code 983

It's also possible that some cars **may** have come with different tachs due to different assembly plants or parts shortages. Again, ultimately to prove that exception you would need an original build sheet to see what code is in box 72.

To verify if your tach is original and not a reproduction, the face has 3 little screws in it unlike the reproductions. In addition, on the back of the tach mounting plate the complete part number is stamped in a blue colored ink. So for instance, the 5000 rpm tach would be stamped 6469938 and the 5500 rpm tach would be stamped 6469985. The last 3 numbers (in this case 938 or 985 for the 2 examples) are the correct codes in box 72 of the buildsheet.

As noted above, Atlanta LS5's (SS 454 cars) commonly came with 5000 rpm redline tachs.

Exceptions to the above may exist, but I believe they would need some sort of documentation to validate the installation.

This is a derivative observation and is applicable to more parts than just tachometers, but...
I see posted here all the time that the assembly line would use whatever they had or make mistakes. So, it appears likely that even though the buildsheet may call out a specific part, that part *may* not have been installed in that car when built on the assembly line. There was a discussion the other day about fans/clutches on LS6 cars, then this thread is why I bring it up.

I know where an original 72 El Camino is with a 5000 redline tach. It is not an SS, but has the round guages. Because the tach was ordered.