CurSedVoyce
California Hillbilly
You can either switch out the one on the truck to a 7 blade or, they do make an adaptor, or you can. Not rocket surgery
I thought soldering was a no go on vehicles, since it is more likely to fail than a rimped connection. Personally, I'd do both. Solder for a good connection, and crimp, so it doesn't come undone and short into something else if it overheats.