Just use the 10/12 yellow butt connecters {either end will work}. I like the heat shrinks but they are hard to find and have always had good results with just properly crimping. If you don't get the heat shrink connector then complete every crimp job by sliding some heat shrink over the connection.
It is a good idea to keep and assortment of connectors, butts, rings, spade, bullet etc. along with a quality crimping tool as part of your tool collection that travels in your rig. Having wire in the more common gauges of various lengths can be a game changer as well.
:C
