will a 1978ish dash cluster fit in a 1985?

[Bone85K5]

Any thoughts?

 

[Bone85K5]

will a 78ish tach fit in a 85?

 

[the professor]

YES IT WILL....I have a 1978 K20, and it is using the cluster out of a 1989 Suburban...(donor vehicle...)
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I traced the wiring, the plug and the printed circuit...the wiring is identical...it is even the same weather you have a tach and the small fuel gage, or no tach and the big fuel gage...just plug it in
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the tach is wired seperately...
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There is a slight difference in the angle of the crystal covering the display, but it will fit...use a bezel from the later will work, just don't use one from a DIN radio...(it is squared off in the lower right hand area, below the radio, and will hang off the later dash