Son bought a 63 Riv. & wants to pull the shorty headers. Have been told they are specific to the Riv. car has a 401, don't know if 425 will work. (Nailhead Ignorant) JR Wills
Thanks Ted. Like I said I am Ignorant on Nail Heads, although I do remember something different about the GS "A" cars being different. He wants to pull the Shorty headers off & replace them with Stock manifolds, although Match #s as to Block/Trans & Body, don't care about #s for manifolds. Not a Number's Nazi. LOL JR
Here's another source up here in Pa. https://bestoffercounts.com/ Larry's likely has nicer parts since they're not from the rust belt. Skylark GS does have different exhaust manifolds.
My cousin has a few old Riviera parts cars. I can ask him he he has a set of factory Riviera exhaust manifolds that will fit a 63 as well ask if the 401 and 425 manifolds are interchangeable.
My cousin just replied to my message however only stated that 63 through 66 Riviera exhaust manifolds should be the same however the numbers might be different for each year. If you are still looking and are interested I will message him again to see if he has a set. FYI Both myself and my cousin reside in Winnipeg Manitoba Canada.
A '63 could have the heat riser built into the manifold whereas the '64/'65/'66 have a separate heat riser. Either manifold will fit just be sure it comes with a heat riser valve IF NOT an original '63. Tom T.
Thanks to All who answered. Son found a set, missing the Heat riser, & Hector came through with that. Son is currently in South Carolina, working, & I haven't had a chance to get in the shop to work on it this week. We May still be in the market, so if so, will reach out. ( never know if a Spare set could be needed, LOL) Thanks Again JR