Which printed circuit do I need? '80 or '81?

[Boostaddict]

I have a 1980 all original GMC truck that has the 85mph base cluster (picture below).  I want to install a '78 tach cluster but the printed circuit is in horrible shape.  The aftermarket printed circuits I see are either for '78 to 80 trucks or '81 to '87 trucks.   I'm assuming I need the '78 to '80 circuit but wanted to double check since I see clusters that look identical to mine in newer trucks also.

Thanks!
Wayne

[topp]

The tach is not driven off the printed circuit.  It has it's own wire harness.
Use the one for your year truck.

[Boostaddict]

Thanks for the quick reply.  Thats what I thought but since I've seen this style cluster used on the newer trucks too ('81, '82, etc) I wasn't 100% certain that a '80 circuit will work.  I'll give that a try and see how it works.

[Captkaos]

1978-up clusters will swap, so the only real difference is the font and the speedo only goes to 85 on the 80-ups.