Corner lights short out when turned on. 67 c20

[charles_c12]

Ok I have a 67 c20 2wd lwb it is bone stock base model no option truck. When I turn on the park lights the fuse blows. I have replaced the head light switch with 2 different new ones and it still blows. I have brake lights until I turn on park lights. All other circuits are ok and the is no add on parts under the dash tied in. I do have a trailer brake controller that will activate the brake lights also. Any help would be great as it's my only rig and the days are getting shorter.
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