Hello everyone, my friend said hes going to buy a 88' trans am GTA with a stock 305. I thought all the GTA's always came with the 350 TPI. Could someone please tell me this so I can let him know? Thanks

Mark

 

Depends... is the car an auto or 5 speed? 5 speed cars all came with the 305.

 

Yes, you could get a 305 in a GTA. The 8th digit of the Vin# should be an F.

 

I just checked out the GTA Source Page website (http://www.gtasourcepage.com/88RPOFigures.html) and according to the RPO code production numbers, in 1988 there were a total of 9765 GTAs produced in 1988. Of these, there were 809 five speeds. But there were 2852 LB9 305s the same year. That means there must have been a few 305 GTAs made in 88.

 

A friend of mine just bought an 88 305 auto GTA last weekend.

 

I was always under the impression that all real GTAs were 350 L98 / Auto unless the 305 / T5 was ordered. I believe the LB9 / T5 was a delete / credit when ordeded.

88firebird: sometimes the GM production numbers don't make sense. As an example, see this thread

Also:

By the same logic, there were 2,043 GTAs made with no T5 and no 700-R4, but they did get a driven speedometer gear.

What you may notice on the GTA site you linked is the following:

D3Y -- Gear, Speedometer Driven -- 6,913

which perfectly lines up with the automatic cars. Makes sense.

Now,
D4D -- Gear, Speedometer Driven (25513047) -- 2,043

makes sense, and yet doesn't. Because the total of cars built with D4D plus the total of cars built with
MK6 -- Transmission, 5-Speed Manual -- 809

equals the number of GTAs built with an LB9.

And yet, the part number is for a driven gear for a 700-R4, not a T5. (Actually, that is easily explainable; they often re-use RPOs and those GTAs which got that RPO definitely had 5 speeds because they didn't have an automatic.) So you've got at least 2,043 T5s right there.

Basically, two theories for you. One is:

The LB9 / T5 GTAs got their
MM5 -- Transmission, 5-Speed Manual Provisions -- 809
or they got their "provisions" piecemeal via MM5 etc. That would explain why the above numbers add up to equal the LB9 GTA production.

Another theory is that they changed their RPO counting methodologies midyear like the above thread I linked you to.

But I stand by my first statement and the math presented herein, and that the GTA RPO listings are accurate in what RPOs various GTAs got, but they are not indicative of T5 / LB9 combined production unless interpreted as I outlined.

 

GM made and sold plenty of GTA 305/Auto combos. There were 3 drivetrains you could get in a GTA:

350/700R4
305/700R4
305/T5

Both 305 engines were listed as a credit on the option side of the window sticker. Why anyone would save a few bucks to get a 305 auto, who knows. Sometimes things just dont make sense.

 

Thanks for some thought prevoking info there JMD... I realize that GMs production figures aren't going to be 100% accurate... but from what I've heard (and seen on several cars) 305 autos were available. I agree with Madmax... why on earth would you want a 305 auto in a GTA? Some GM options just don't make sense... I've heard of the odd GTA being optioned with rear drums... why on earth GM would do something like that blows my mind...

I guess if you want to authenticate whether or not its a GTA for sure, check out www.gtasourcepage.com under authentication tips, and if you still have questions, contact the guy that runs that site. He seems to know his GTA facts.

 

The fact about Drum rear brakes on some cars was GM ran into a parts shortage of Disc brake rotors and used Drums to continue production. Forget what year 90,91 or 92.

Also if you bought the car new, most of the time it was what was on the dealers lot. Special order cars was just not happening at most dearlerships. Try walking into a dealer today and try to special order a car.

 

i belive it was 91-92 that ran shortage probs with disc. I seen too many 91s with drums insted of rear disc. Which kinda sucks

 

I think that the rear drums came with the 305/auto combo, definitely as early as '90 (My sig is a perfect example).

As for why bother with the 305/auto, GM eventually decided to stop sticking 350s in t-top cars during the '90 model year. So, if you want a t-top car with an auto tranny (Hey some people might prefer the 700R4 over the T5...) you'd be limited to a 305.

 

Now that makes sense to me.

The engine credit delete was total news to me. Thanks for the info, guys

 

Rear disc brakes were a option (RPO J65) on 305 cars and a requirement on 350 cars. You paid for this option, GM gave nothing away.

 

I totally forgot about that... I remember now, reading that GM didn't like offering T-tops with 350s... cars twisted too much...