Oh yes, GM was good at mixing SAE and metric. Like the alternator on our van that had one metric and one SAE bolt. Needed both socket sets to change it.
OP: Might look around and find a small set of assorted tools. I once bought a Craftsman set that had socket sets, pliers, screwdriver bits (torx, phillips, flat), channel lock pliers, Allen keys for about $30 that all fits in a neat case. Cheap, but it has come in very handy at times. A similar set may cost a little more nowadays, but I'm sure Harbor Freight or other places have similar tool kits.