Roderek Soest at ididiesel.com is back at it, his kits are $250, I put one on my 91 F-Super Duty service truck and couldn’t be happier. Very nice kit, definitely worth the money.
That doesn’t include a pulley, so putting together your own kit might be quite a bit cheaper, just make sure to use a 200A megafuse if you get a 130A 3G alt, they put out more than their rating