Adding some lights, which alternator do I have?

[waylap1]

I'm thinking of adding some additional flood LED lighting to the front on the tip over wings but want to make sure I don't draw to much current. I like these
http://sirennet.com/soewlf0500dbdf0w.html
24 watts for 2 and 2 amps. What's the easiest way for me to tell if my 91 ST already has the 40 watt Alternator and if I don't have it, will these still work if I'm also running J&M comm system with a fairing mounted stereo and a LIN3 on the rear?

 

[sirepair]

With either alt you should be OK. Easiest way to tell is to look up under the left-rear corner of the engine (photos HERE, check bottom one) and visually inspect the alt. Original 28 amp unit is oil cooled and basically looks like a big bump on the back of the engine. 40amp is an air-cooled unit that looks like it was swiped from a small car. There are open vents on the side of it. Another way to tell is to remove the left side panel and see if the regulator is in place and wired up. 40amp has a built in regulator. While in there, check/clean/dielectric grease/tighten connections. LOTS of posts on these issues.