You said 6 pin flat on the truck, do you mean 7 pin round or mean 4 pin flat or something else?
I have not seen a 6 wire flat on the back of a modern truck. 4 wire flat for standard non brake trailers and 7 wire round for brakes, yes.
They actually make 4, 5, 6 and 7. Just the 5 and 6 are not common on modern trucks from the factory.
Trailer Wiring Diagrams | etrailer.com
Can you link the product you bought or take pics of the ends. Something is not adding up exactly right. Once we see what you have can make better recommendations.
Hope this helps
John
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Current Sunlines: 2004 T310SR, 2004 T1950, 2004 T2475, 2007 T2499, 2004 T317SR
Prior Sunlines: 2004 T2499 - Fern Blue
2005 Ford F350 Lariat, 6.8L V10 W/ 4.10 rear axle, CC, Short Bed, SRW. Reese HP trunnion bar hitch W/ HP DC
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