Yamaha to merc

Hi I am going to be installing a 1989 or 1990 Merc not Shure and I am going to install it on a 2002 glasstron sx170. The glasstron has Yamaha control and harness. Is there any way to use the Yamaha control and harness ? Is there and adapter I can get? Do I have to change out all the gages.and any other info you could shares would be great thanks

There is,to the best of my knowledge,no adapter as Yamaha used different colour codes to Mercury and nearly every other manufacturer.The cables are also different,though there is an adapter for the engine end on teleflex,ultraflex.Best option,IMHO,sell the Yamaha controls and buy Mercury.
It will depend on the type of gauges,if they are Yamaha specific,you'll need to change them.Faria,Teleflex etc.,can be adjusted accordingly.
The bracket bolt pattern will be different as well,leaving you with a few holes in the transom that need filling.