Hi and welcome to mightyram. There is a threaded bolt hole in the side of the block under the A/C mount (it's sort of in line with the mounting bracket bolts but set back a bit) The bolt has a hefty sized head on it too - 17mm. Everything is going to need a big clean to ensure a solid ground. Use non caustic oven cleaner and an old brush - it will make short work of it (having a pressure washer will help too) This would be a good opportunity to go through and check all the ground leads and clean the crud off them. Bad grounds cause all kinds of electrical glitches.