FWIW & IMHO:
I would never buy anything made by Wells either.
Way too much bad publicity on that manufacturer.
I like to keep my car original whenever possible by buying GM
There are several retailers that sell original GM products considerably less expensive thatn GM.
GM Parts Direct, for example, GM PN 24503624:
GM list price: $ 261.80
GM Parts Direct price: $ 130.90
GM Parts Direct shipping & handling: $ 26.18
$157.08 total to your door, not that bad for a brand new GM part.
Not near as good as the "Go to the junkyard and get it yourself" price.
HTH
I think that John's Perfomance and some other retailers sell this item.
I believe that John Dicarlo, alias RedRegalT, also sells used back-up units reasonable.