Have you removed the radiator and front panel. With them removed the space freed up, transforms this job. To get radiator out, undo four bolts that hold slam panel on, pop the water hoses, and unbolt cooling fan from radiator. Leaving cooling fan where it is, you should be able to slide radiator up and out. With this and headlight out you have all the space required. Get a decent ring spanner and with the aid of another spanner hooked over end you should be able to crack bottom alternator bolt, then with other bolts removed from plate that goes to ps pump and bar that goes to inlet manifold, you should be able to tap through alternator bottom bolt and manouvre alternator out through headlamp recess. With radiator still in place its hard to get clearance to work round alternator. Besides take the oppurtunity to flush radiator at same time (I was amazed at crap that came out of mine)
