So relative newbie on the newer Olds 455. I have a 394 that I am knowledgeable of and plan to swap that into a 52 Chevy Ute. But this post is about a newly acquired 455 and T400 that I plan to put into a 50 Chevy pickup, on a S-10 chassis. I have figured out a few things, but have a few questions on exactly what I have.
Engine is 396021F, and has julian date 2577 (hard to see the last 7), and stamped 38D103383. Has C heads (yay!) and an Edelbrock Performer Olds 455 intake.
Trans has75-OA-54268 and is a Turbo 400 long tail.

So my questions: Is my block a later 1977 (257th day of 1977)? Put into a 1978 car? Where do I find a date code for the heads?
Trans plate: I think might be a 1975 and OA means Oldsmobile division?

Being that my engine is obviously not original, I have no idea if it has any internal changes like higher compression or performance cam. Happy to get the better heads than typically would come with a 70s smogger 455. I have though about pulling a plug or two and look into the chamber to see piston top shape. Here are some pics of my engine and trans. Seller had this for 26 years sitting in his garage, and got it with a 70 Pontiac Lemans he purchased. He kept the Lemans all Pontiac and never ran this engine so knows nothing about it. It does turn over, seems good compression on slow turning the crank bolt. Thanks for help to get this all identified, Terry

 

C heads are 1967-1969 era. The 8 on the block would be 1968, which matches the heads.

 

The 75 OA code means it’s a 75 Olds transmission. I don’t have my book with me, so I can’t narrow down exactly what the original application was.

Sound like you have a decent start.

 

So what I have is a late 1967 block with the 2577 Julian date? 257th day is Sept 14th, I looked it up. That would have been in a early 68 model car, as from the 38D103383 stamped number? I guess that is good to hear, the engine may be original except for the Edelbrock intake and carb.

Thanks for confirming what I thought.

 

396021F is a 455. Since its a 1968 block, it would be an EARLY 455. The only cars (except the 515 Hurst/Olds) to have a 455 would have been from a B body 88 or 98.

A late '67 block would be a 425 with a casting number of #385244.

 

The cast date code is 257. These were changed on the molds every day. They were held on the molds by screws. Where I worked 2 slotted screws meant first shift. 2 philips screws meant 2nd shift. One of each meant third shift.

 

Mine is definitely 396021F casting on front by water pump. Would oil pan shape or exhaust manifolds help narrow down? The oil pan is like a two stage sump, with a mid level drop and then the big sump. See picture. The exhaust manifolds are number 1 and 13 ( I think, the 3 is tough to make out). The 13 passenger side is definitely strange shaped. I realize manifolds and oil pan could be changed out pretty easily. Thanks to all for the help.

 

Quoting myself since I have been doing some searching on the site here and becoming much more educated. I found answers to some of my questions. The Number 1 LH manifold is a 65 330 exhaust manifold, casting number 411961. Haven't found anything on the RH manifold yet, but apparently is quite similar shape to many other RH manifolds for single exhaust with the crossover pipe. I can say that most likely I will need to find a different manifold to use on the 50 Chevy pickup since the engine will be back right against the firewall and that will need a manifold that goes down rather than back. Or maybe find some headers that may fit or need slight modification to work with the S-10 chassis.

The oil pan is just a std big block Olds shape. Nothing to be learned from that besides would be correct for the 455.

 

The 563619 manifold is for 1977-1979 403's in a Pontiac, according to Firebird Central.

 

How would that fit on a 455 block?

 

Your exhaust manifolds are cast with a "1" and a "13". These are small block exhaust manifolds.

 

Best I can tell you have an early 455 made for big cars from model year 68 which is late calendar 67 bolted up to a 1975 TH-375 seen in 350 powered 88s. I am thinking someone scarfed the trans to repower the old 68 before that, too, stopped.

The trans is nothing special, but the engine is high compression. Small valve C heads, but a valve job and a nice cam could make that thing pull stumps after a rebuild.

 

Note the word, "Dorman" on the freeze plug in your picture above.

 

I'm back after a day at Hershey swap meet, so here's the scoop.

The OP has a 1968 455 block. The last 455 was cast in the 1976 model year, The "D" in the VIN derivative stamp is Doraville, GA assembly plant, which only built Delta 88s in the 1968 model year. The 257 julian date on the block would indicate Thursday, Sept 14, 1967, so this is a pretty early 455. It MAY have a forged crank, but don't hold your breath.

The RH 513619 exhaust manifold was only used on 1977-79 Firebirds with the Olds 350 or T/As with the Olds 403. It was also used on 1979 Cadillac Sevilles with the EFI Olds 350, but only in Calif. Note that this manifold has a casting bump for the O2 sensor bung, though it appears not be be machined in this case.

The LH 411961 exhaust manifold was used pretty much across the board on RWD small block Olds motors from 1973-1985, including diesels and the aforementioned F-body cars, so both sides may have come from a Pontiac. Yes, obviously these bolt to a 455 and Olds even used this manifold on 1975-76 455s from the factory.

The trans is a 1975 OA trans. OA is usually a TH375, which is a light-duty version of the TH400 with a small diameter output shaft and long tail used only in small-block powered Delta 88s that year. Check the underside of the tailhousing, which will have 375THM cast into it. Not nearly as strong as a TH400, despite using the same case.

 

Thanks to everyone for the extra information. Especially to Joe, who nailed it with the TH375. I checked and sure enough has the exact 375-THM cast on underside of the tailshaft as shown in his picture example. I thought the output shaft seemed smaller than I recalled for a TH400, and the fact is the output is smaller. But for what I have in the deal no complaints. Now just decide to run that TH375, or consider going with a 200-4R to pick up OD. Realizing that the 200-4R needs to be a built up one to handle the torque, not just a junkyard take-out. OD would be nice with the 3.73 gear for highway cruising.

 

The TH375 can be converted to a typical th400 with a TH400 output shaft and extension housing. That model will almost certainly have the flimsy stamped steel pistons in the drums, and plastic accumulator pistons. It will also more than likely have the thick pistons, meaning 4 friction discs instead of the common 5.

If you are having the transmission rebuilt, the cheapest/easiest fix for the low clutch count and stamped steel pistons would be bonded 4L80 pistons. You need TWO DIRECT pistons, you can use the direct piston in the forward drum if you omit the center seal from the forward clutch. The only downside is a slightly faster engagement into drive. Aluminum accumulator pistons are common.

 

All of which is relatively easy to source here in the US. Probably not so much for the OP. Even here in the US, it will be less expensive to start with a real TH400. If the OP can find one with a busted case, the TH375 case is the same and all the TH400 parts drop right into it.

 

Without a doubt, easier and cheaper to start with the 400, especially if you plan to really turn up the wick with big power. But so many people make the mistake of buying a 375 and then finding out it’s not the same I figured I’d share the info.

Did I miss something in the conversation in regards to location? I didn’t see anything about overseas. I just checked the OP page, says he is in Cincinnati. I know for a fact there are a couple of WIT (Whatever It Takes) dealers within 75-100 miles of Cincinnati.

 

Sorry, I saw the ute and ASSUMED...

 

I am located in Cincinnati. The Utes are just some of my other cars, which were originally built in Australia. But they are imported to USA. I imported two of them, and one purchased here already.

I'm still determining what to do for the trans in my 50 Chevy truck project. This TH375 was just part of thr deal when I bought the engine which is what I was really interested in. I'm sure the TH375 could be strong enough for my plans on the engine being just a good street driver. Big question is do I consider a 200-4R with the OD. That would work nice with 3.73 gear rearend I have. However that's the additional money option.

 

I remember to look at my book today. A 75 OA 375 was originally used in an olds 88.