The back of the cluster looks like the 70-73. The plug receptacle is longer on the early clusters. Also the printed circuit's alignment pin is in the same position as an early cluster. In other words...nope, won't fit. Here is a pic show what is different. Notice the early cluster on top has less wires than the 74-up cluster on the bottom.
aguerra186, this tech article may help you to make it work in your 77: http://mmb.maverick.to/showthread.php?t=31291
It can be made to fit I did this on my 77. You have to do some surgery on the plug or the cluster, I don't recall exactly what though , but it does work after doing the mods.
It didn't look like it would work with the 74-75 circuit board without cutting half way into one of the circuit tracks. The 76-77 circuit board could be made different enough that the track cleared the receptacle hole.
