About the tow mirrors,
I bought an Ebay set for my 99 chevy (88-98 body style) manual adjust but with the LED signals and they are great, really love them. I only bought the LED ones because they didnt make the plain ones when I bought them. Paid $230 but they have come down since then.
I liked them so much I bought a plain set for my 99 GMC (99-06 body style) off Ebay for $142 and they flat out suck. They are on a bad angle, kind of tilted too far back which dosent allow the mirror faces to be moved far enough outward so you cant really see the other lane of traffic or your trailer without physically moving your body forward to get a good view. What they DO give a great view of is the side of my beaten up truck. Even in the extended position, they truely suck. I am going to try taking them apart to see if I can make some sort of adjustment.
Some of the aftermarkets for 99-06 are ugly IMO, look at the truck from front or rear, and the mirrors do not sit level enough, they are really tilted up on the outside bottom.
EDIT: Forgot to say, you may be able to find some cheaper, as they make them for 88-98, 99-06, 07-new and either way you have to make mounts so you have some flexibility as to what you buy. There are several 73-87 trucks Ive seen over the years that make a plate to replace the vent window, you can make mirror mounts on that maybe, but I think with these tall mirrors might be too high up there.
Heres something that can give you a better idea, the yellow truck has 99-up superduty mirrors which are similar
http://67-72chevytrucks.com/vboard/showthread.php?t=487621&page=2
Have a look at how the 88-91 electric mirrors mount, that height is where you would probably need them, just at the bottom of the vent window since the 88-91 blazer suburban, astro/safaris and 88-98 GM's use the same mirror heads