Before I had to quit working due to my health, I worked for a company that had a GMC Safari panel van with aftermarket power windows. Basically, what this was was a motor that literally mounted on the splined shaft where the crank handle would ordinarily go. I believe they may have come from JCWhitney. I asked about 'em one day, and they told me the kit was really cheap. Cheap or not, they worked pretty well.

Not sure about their power lock kits as I have no experience with those. But I understand they work well from people I've talked to who've installed them.