Just wanted to add my 2 cents to the topic. Succesfully removed and replaced a dead starter last night on my new 740. The top bolt is F'n nightmare to break loose. I tried the 2 extensions and wobble joint method from below, which some have suggested, for about 1/2 hour before getting pissed and going back inside to read up on the topic on the BBoard. Came accross older posts where the top bolt was described as "the sweat of Satan's nuts"....ruh roh raggy! Thankfully came accross an old Art B post where he advocated using an old Sears 12" long open end wrench from the topside along the firewall. Ran back out Sears and got one. BTW mine was an 18mm not 19mm. Lots of crap in the way(heater hoses etc) but it can be done. Gloves a must as my hands look like hamburger today.
Hardest part was breaking it loose. 55 foot lbs my ass! I got wrench on it then used piece of oak 1"x1" to lever against the rear engine lift point. Broke 2 before it creaked and let loose. The you only have room to loosen 1/8 of a turn at time! All the while hunched over...in 25 degree weather. If you can find naive garage that will do the job for an hours labor(and you can afford it), LET THEM DO IT!
PS Job complete and she is back on the road.
PSS Thanks Art