Gauge cluster question for 75 C10

[Dead Parrot]

Is there any difference in the cluster backing plate between 75 and 78+ as far as how it mounts into the dash opening? I know there are differences on the gauges themselves, oil(mech vs elec), amp vs volt, etc.

My current one is literally falling to pieces and has two previous custom gauge installations in its history. I am considering building a new cluster from scratch. May include an aftermarket tach/gas gauge and use LED back lights. I know I will have to repin/modify the connectors to match whatever gauge setup I go with.

Don't want to find at the moment of installation that my 75 has a unique cluster mounting setup.