Semi truck lights

[Belairconvertable]

I am building a model semi truck for the first time. This is the Gmc general.  I was wondering what the 4 plugs in the middle of the picture. Are they used at all? I can't find them in the instruction manual either. Any help welcomed. 

[Jim B]

The red & amber trees that AMT puts in there semi truck kits are generic.  You won't use 90% of what's on the tree in any particular model.  

The four large "plugs" are for warning lights on wreckers (amber) or fire apparatus (red). 

[Belairconvertable]

Thanks for the information!