How to identify my pulleys??

Well i have been chasing a charging problem with my (new to me) fox. If i let the car idle for extended periods with accessories such as cooling fans and blower motor it will drop the gauge to the red and with a voltmeter on the battery it will go down to 12.5-13.0 volts and it drives me nuts. I have since figured out my car has underdrives on it and i want to know how to identify which ones are aftermarket, what type they are, and if i could look into over driving my alternator. But without knowing the size/manufacturer im not sure how id know which pulley to use and do the math as to not over rev the ALT itself. i plan on doing a 3G upgrade as well and would not want to over rev that one either. here are some pictures of them any advice on WHICH are aftermarket and any size ideas would be helpful. BTW Ill trade straight up for anyone wanting underdrives for their stockers i have a listing in the classifieds

NOTE: if anyone has stockers to sell id be interested in purchasing those as well!

View attachment 137774
View attachment 137776

Thanks guys, went and picked my 3G from the local PAP yard it came from a 3.0 taurus and looks brand new! I will be getting that in as soon as my install kit comes in. Picked up a set of contour fans as well u fortunately only one of them work so I will be returning at another date to exchange those out luckily I bought the 2.00 warranty

I do not believe it comes with a ground but I will probably use a starter ground cable from the local parts store. Is there a kit out there that comes with a ground?