Get a Dakota alt (90a, 120a, whatever) and the March bracket will work. Did it on my 440, so I can't speak to SB. It's not what you would expect but it's a bolt-on. As you can see you only use one bolt under the alt for the adjusting bracket. I need to get a March pulley to match the newer alt, but it's been running for 2 years like this. Upgraded wiring to handle higher amps and you may have to shorten the positive stud (close to head).