Rather than "roll the dice", you need more conclusive tests. Any FLAPS can load test the batteries. If you drive the truck in and have them test them in the lot, remember to disconnect one negative to isolate the batteries, no matter what the counter dude might say to the contrary. They should also be able to test the starter, but their component tests are only as good as the tester. If you can find one of those old-school shops that rebuilds auto electric components, where they still smoke and curse in the shop, their folks have a lot better "ear" for testing starters, alternators, etc. And if your starter is bad, a rebuild at one of these places will most likely outlast any "lifetime warranty" offshore reman cr@p at the FLAPS.
Harbor Freight sells a 100A load tester, $20-ish, that will at least give you some clue as to the condition of the batteries. For $50 you can get a 500A carbon pile tester that will put just about any battery through its paces.