I'm putting in an order to Summit for a 140amp powermaster alternator and was wondering what clocking I need. Straight or offset? My car is an 87 with the V-belt setup. Also, I presume it's easier to get the OE wiring version as opposed to one wire which, is for some reason, far dearer. Thanks for the help. Robert

If "clocking" means the relationship of the mounting bolts on the front to the the angle the plug goes into the back then it doesn't matter. I've had to "adjust" several alt. over the years. Just remove the four bolts that hold the front and back cases of the alternator together and spin the back around till the plug point the right direction. Then reinstall the four long bolts. Works for me.

I thought it would have had something to do with the bolt pattern? Do the V-belt and serpentine systems not use different alternators?

Don't know if the alternator is different. The pulley on the front most certainly is different. The v belt alternator has a one, or two, groove pulley with deep v notches. The serpentine belt pulley would be much wider and have only very shallow grooves in the pulley. There is some difference in the physical size of alternators as well. I've only bought one for a 3rd gen (83Z28) and the parts place got it right the first time. Had to make a couple of trips for the one I put on the 81Z28. The first one they sold me was a little on the small side and wouldn't come close to bolting up to the adjustment bracket once it was bolted into the pivot bracket. Again, not sure if "clocking" refers to the orientation of the front/back of the alternator or not, but I have had to sping them 90 degrees before to get the plug on top instead of against the valve cover.