I inherited my dad's 1975 Olds Delta 88 royal convertible. It has a Pontiac 400. I have tried exhaustly to find out info on the vin number. I have gotten info on everythimg except the last 6 numbers. When I try to look it up I get invalid vin. I would really appreciate any help any could give.

 

That's because pre-1981 VIN don't have enough characters for these modern VIN decoders to work.

Your VIN probably looks like 3N67R5Mxxxxxx.

3= Oldsmobile
N= Delta Royale
67= convertible
R,S = engine code w/ Pontiac 400
5= 1975 model year
M,D,E,R...= assembly plant
xxxxxx= car's sequential serial number

A derivative of the VIN will be on the engine block and transmission. Not sure where Olds located it on the 400 engine; Pontiac always put them on the right front of the engine below the cylinder head.

My sources show 245 1975 Royale convertibles got the Pontiac 400 which was also used in Ninety Eights and Custom Cruisers.

 

Thank you sooo much for the info!! It is very much appreciated. The last 6 numbers are 114818. I was also told it is important to know what number made the car is due to the 400 engine. Is that correct?

 

That only matters to unthinking auto parts store counter workers who can't sell you a part unless the computer tells them to. The fact that you already know it has the Pontiac motor means that you have a leg up on them.

 

The engine code is what's important in that VIN. Even then no guarantees a parts store computer will get it right esp if it's set up to recognize R as an Oldsmobile 350, which some years it was. If it fuddles their computer say for spark plugs or engine emissions stuff, tell them to look it up for a 1975 Pontiac Catalina 400-2 barrel engine.

As to why Olds used the Pontiac engine, I don't know. Probably something to do with emissions certifications but possibly limits on engine production capacity.

It's telling that there was no owner stink over the 1975 Pontiac engines like there was two years later when Chevrolet 350s got stuffed into Delta 88s because Oldsmobile had oversold Olds engines to Buick, Pontiac and Cadillac and then didn't have enough engine-building capacity to supply their own cars for their first year selling a million cars. To honor their inter-divisional commitments while keeping their own assembly lines going, they had to buy engines from Chevrolet.

 

If a parts store asks for a VIN, run, don't walk, away. I strongly suggest researching the correct part number first, then just order the P/N you need. Nearly every on-line parts vendor's catalog has major errors when it comes to Oldsmobiles.

 

www.northernohiooldsclub.com if you're looking for Oldsmobile people in your area to hang out with.

Also strongly recommend getting the 1975 Oldsmobile Chassis Service Manual and the 1975 Fisher Body Manual as a start to help you and anyone you hire to work on the car understand and service it. Later you can think about getting the 1975 Service Guilds and Tech Bulletins.

Mid 70s were a time of transition for Olds and the more service literature you have, the better you'll be able to take care of your car. The people who serviced them as new cars are all retired or dead by now, and people used to computer controlled cars won't have a clue.