I had the same problem, only laps in the back. Boy was I pissed when they offered three-points in 90. After all these years I finally upgraded last month. Do the junk yard thing, make sure the outers latched will work in your inner (female) buckles. The mounting holes are already in your vehicle, just make sure to get ALL the bolts, washers from the donor. The upper plates will be needed to back your holes. I am told the old ones will punch out, but I made new ones because the yard refused to remove the old ones. Dont forget the plastic bushings that go into the fender wall trim.
All in all, an easy mod in a couple hours.