Try to match the wire size, if you can, mostly to avoid overheating the smaller wire when soldering , Install "shrink tube" before you twist the wire, for both joints, use a thin electronics solder, and a dual heat solder gun on low for that small a wire. Shrink the tube with a match or hair dryer. Good luck.
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.