I believe the fitting on my '87 was a 15mm. I found the tensioning of the belts to be a little challenging. You have to loosen the bottom bolts of the alternator (front and back) and loosen the top bracket bolt and also the bolt in the adjustable area of the bracket. I took the adjustable bolt out completely when I tensioned the power steering belts, this let's the alternator pivot freely. On the power steering pump, the bracket for the alternator is attached to the same bracket. I took out the back bottom bolt completely and loosed the front two. There is a square hole in the power steering bracket to put a 1/2" drive ratchet in, but I found I could get any tension using that. I ended up flipping the generator toward the engine and used a ratchet strap to pull tension between the two until I had about a 1/2" or so of deflection on the power steering belts, that didn't feel too tight. I was mindful that with dual belts there is a lot of force on the bearings. After snugging the power steering bolts, the alternator belts are easy. After I run it a while, I'll recheck the belt tension.
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