Long story short, I've got a LT1, and I'm not sure what year it is. I am kind of suspicious that its not a 95 like I was told by the guy that sold it to me. I'm pretty sure I saw on the throttle body the clock style date stamp with a 93 in the middle. The exhaust ports are D-shaped, and I thought they were round on the 93s and D-shaped on the 94-95s. If its not a 95 like the guy said it was, looks like I'm in for some fun when I wire it up. So how do I tell what year it is?

 

93s had D ports as well.
Check the bottom of the opti. If there are two small vent tubes coming out towards the driver side, it's a 95. Otherwise a 93-94.
Also, 93s on the fuel rail, had only one crossover tube in front while 94-95 had two. (front and back)

 

If I recall, there is only one vent on the opti, downward at about a 45 toward the drivers side, and there are 2 crossovers on the fuel rail. I guess that makes it a 94.

 

Nope, no vents at all on 94s.

You can also find out this way.

 

I'll check the serial number. Thanks!

 

Somewhat unrelated question: Why do some advertisers say that 93 and 94/5 headers are not interchangeable? I've been shopping around for some LTs and thought it was because the ports had a different shape, but since I've been enlightened, what's the difference?

 

It's because of the AIR system. It's different on 93s, but if you get non emission headers, they'll interchange fine.

 

basically the AIR tubes that screw in have larger diameters, i had to get 93-95 AIR hoses for my car when i bought my AS&M headers, the physical design is the same, except 93-95 had 1 cat 96-97 has two.

 

The differences on the 93's are a little more involved than that. All the single-cat engines (93 - 95) have the same diameter AIR connections. The problem with the 93's is that the locations of the AIR connections is different.

 

is it just the pass. side AIR connection is moved further to the front of the manifoldon the 93-95?

and Inj. i was saying i had to get diff diameter due to the fact that i put 93-95 headers on my 97. thats the only converging difference that i think i came across.

 

I checked the number, and it's a 94. I knew that a** lied to me. Anyway, can anyone think of any wiring differences between 94 and 95 off hand that I may run into? And is the intermediate pipe on the V6s the same as the V8s from the cat to the muffler? I want to keep the catback, and go with new headers (obviously), y pipe and cat delete pipe.

 

If you have a 95 harness, you are all set. (unless you don't have the 94 opti harness) If it's a 94, there will be a few issues.

Junkyard people will lie 95% of the time from my experience with buying LT1s.

 

I have the 94 harness and PCM. I didn't look to see what year the trans is, but I don't think it matches up. It was all wired up when I got it (engine that is, trans was separate). He told me it was out of a 95 T/A M6. Despite the trans not wiring up, what issues will I have? I think the 4 plugs that go to the dash harness are the same. Am I going to have to get a new PCM if it was for an auto?

 

The connector on the 94 engine harness should connect to any 94-97 tranny. If it doesn't connect, you either have a manual tranny harness or the transmission is a 700R4. (or something else)
There will be a few wires that need to be swapped around in order to make it work besides that. I might post details later on if I have time.

 

The trans is a M6, and I think I have an auto harness. I think there were more connectors on the harness than there were on the trans.

EDIT: Does that mean the PCM isn't going to work with the M6, if it was originally for a A4?