I need some education. Stock exhaust manifolds for a '66 400.

Fusick sells exhaust manifold bolt/washer sets for $36.50 and bolt-locks for $7.50 each, both for 1964-81. So $66.50 + shipping.

Inline Tube, aka Motor City Super Cars, has this set for $34.95, free shipping, but only for 1968-72? Wouldn't it work on stock manifolds a '66 400?

68-69-70-71-72 442 W-30 W-31 Exhaust Manifold Locks and Bolts Stainless Steel | eBay

 

Not a 66 expert, but did 66 use the locks? Maybe that is why they are not listed for 66, but the one you showed should work. Also, I never use them, and never had a problem with bolts coming loose.

 

They will work for all those years the same but there could be something that makes them slightly different between one year and another for originality reasons.

 

I believe the exhaust manifold bolts are the same as the bellhousing/automatic transmission mounting bolts. The 66's did use the lock tabs. You can buy OEM bolts here
https://www.amkproducts.com/about/

 

Most vendors assume that Oldsmobile only built cars between 1968 and 1972.