well it's not for my yukon, since that doesn't have a alternator at all, so I'd feel better tossing you something atleast. but I also understand keeping one of a shelf and I should probably just do what you did and pick up a 200amp off ebay too. if it doesn't work I'm sure I can sell it on here for about what I paid.
I'm going to try and use it on a 08 c6 corvette. the ones corvettes use are large case oddball. the ecm doesn't send a pwm signal to it to control voltage, just a on off trigger wire. the stock ones charge badly at idle and anything aftermarket is super expensive.
I have an adapter from ict, if that I hope I can use to make it fit, I've found a drop down box in hptuners for alt control. I enabled that and put some random numbers in it and got a pwm signal out on my little pocket o scope. there's a thread on ls1 tech for the camaro guys about what hz to send into a 2 wire to get what output voltage. if I can get the smaller body alt to physically fit, and find the right numbers to put into hp to target 13.8v. it would be a cost effective option for a 200amp alt like you just got off eBay without having to buy a 600 plus aftermarket alt just to get the extra 20 or so amps needed at idle and not explode at high rpm from a smaller pulley. which is what I have now, just a touch over driven and idled up a 100rpm, but it's still iffy on 100deg days idling in traffic with max ac.
so yeah, it's a project I put on the back burner at the end of last summer but summer is about to hit hard here soon again.