I have a project bike i been working on and i finally have it started but just need a seat now! does anyone have one for cheap? it would be much appreciated!

So we have tried two rectifiers for the 87tw the last one fried.question is how do I find out the correct pin out on the rectifier? Can't keep buying rectifiers hoping it's the right one.Any suggestions?? We have lots of voltage out of the stator and it runs fine but won't charge,has to be the...