x2. Yup, taking the OEM 4" rear speaker mount housings and modifying them to accept a low profile (with shallow magnet) 6.5 speaker is the consensus of most VX owners here on the forum. Fellow member "ROWHARD" has an excellent close-up picture of this mod conversion to rear 6.5's using the OEM rear mounting bracket in his Photo Gallery, Page 10, Picture Entitled: "IMG_00152". Luckily; my factory speakers are fine, so I haven't experienced the PITA you guys have (and hope I never do, as it doesn't sound like fun).
I concur on the laudable comments about Crutchfield.com. Over the years; I've ordered many car audio speakers for some of my other vehicles from them, and Cructhfield's enclosed step-by-step instructions are pure state-of-the-art with detailed pictures, and pinpoint tool list for each specific car. In addition, Crutchfield's prices are rock bottom in the industry and they always ship-out immediately the same day the order is placed.
Of special mention-- Crutchfield is famous for their "speaker connector adapters" that simply clip onto the "+" & "-" speaker terminals and then the adapter directly plugs into the OEM factory speaker wiring harness without any splicing, cutting, or soldering whatsoever (these "adapters" are FREE just for the asking when initially ordering your car speakers; however, if you don't ask for them, then you don't get them). The "adapters" are also available for seperate purchase for your specific vehicle from Crutchfield if you already have custody of aftermarket speakers elsewhere. Just FYI.