twistedtree
Guru
I just took a look at teh Deere parts book for the 4045.
John Deere - Parts Catalog
I think you want the 6202 alternator bracket option which appears to be a J180 mount for use with a serpentine belt drive. I can't tell for certain that it's J180, so that would need to be confirmed.
And look at the 3109 alternator options, but just as an example. It's an alternator that seems to use the bracket above, serp belt.
You would also have to change the crank pulley to serp, add a tensioner, and probably change the belt guard.
John Deere - Parts Catalog
I think you want the 6202 alternator bracket option which appears to be a J180 mount for use with a serpentine belt drive. I can't tell for certain that it's J180, so that would need to be confirmed.
And look at the 3109 alternator options, but just as an example. It's an alternator that seems to use the bracket above, serp belt.
You would also have to change the crank pulley to serp, add a tensioner, and probably change the belt guard.