I haven't seen a GMC dash with Tach come up on that auction site. The Chevy will go for $200-300 depending on condition and whether it has the Tach sender included. The senders are either 6 or 8 cylinder. There is an air pressure guage as well. I've seen several write ups on using after market Tach that has a 180 degree face installed in the Chevy dash.

Larry

Ignorance can be fixed Stupidity is forever