I picked up a 9 bolt to swap into my firebird.

It's pretty rusty, I'm sure it's been out of the car for awhile.

The guy said it was an 1LE rearend. Ya Ya Ya. That'd be nice, but everyone swears everything they're selling is rare/collector's edition/special, etc.

The rotors are 11.5" (or thereabouts). They're still on the rearend, so it's hard to get an exact measurement.

The calipers are aluminum (I've heard that only 1LEs had aluminum calipers), but they're also single-piston (I've also heard 1LE's had dual-piston calipers).

I marked a rotor and the pinion yoke, then turned the pinion yoke. One turn of the rotor yields just under 3 1/2 turns of the pinion yoke, so I'm figuring 3.45 gears, what I want.

Both rotors are turning when I turn the yoke, so I'm assuming it's a posi.

Anyone have any thoughts?

While you're changing the fluid (EVERYBODY changes the fluid in a rear they just bought, BEFORE they put it in their car, right?), count the gear teeth.

Sounds like you have an 89 rear. That's the only year of the 9-bolt with PBR calipers.

Probably not out of a 1LE car, as there were rather few of those that year. Not that it makes any difference; the 1LE cars got the same brake setup as any other disc brake rear that year; single-piston PBR calipers with the 11.8" or whatever it is rotors. The 1LE fronts were dual-piston, not the rears.

You might have 3.45 gears. You'll know for sure however after your check during your upcoming fluid change.

I'm going to have the rearend gone through before I put it in the car, but it's not necessary to wait to count the teeth on the gears, the method I used is accurate. They're 3.45s

Finding out what the ratio is isn't my main objective at this point, though. The gear is relevant only in that, according to 1LE.net, the 1LE option for manual transmissioned cars in 88 and 89 had 3.45 gears, so it means it is at least possible that this is one.

1LE.net also says the rear rotors were 11.4" in diameter, which also jibes with the roughly 11.5" I got.

Are all PBR calipers aluminum? I've been told only 1LE-equipped cars had the aluminum calipers. I could also swear I'd measured rear rotors that were only 10.5", which seemed consistent with my being told the 1LE rotors were bigger.

All 89-up rear disc cars got PBR calipers and the larger rotors, not just the 1LE cars.

All PBR calipers (the ones used in these cars anyway) are aluminum. PBR is an Australian company, and I don't know their whole product line; only the part of it that applies to these cars. So, they might very easily make calipers for some Australian models that aren't aluminum, and I would have no clue about that. But for these cars, the PBR calipers that are used, are always aluminum.

All 89-up rear disc rotors are the 11.whatever" size.

All 88-back rotors are smaller, and are used in conjunction with the inferior Saginaw cast-iron calipers.

The 89-up rear disc system is very similar to the 93-97 one, and the 98-2002 one; with the exception of details in the parking brake system. In the 98-up version, the parking brake is actually a set of little drum brakes inside the center of the rotor.

Whoever "told" you all of that about 1LE rear disc brakes being different from the others, needs to be ignored in the future. They are living in some kind of fantasy land. The 1LE front brakes are in fact totally different, in that they got 2-piston PBR aluminum front calipers and larger rotors. Their rears are the same in every way as other 89-up rear discs however.

So your rear is most likely not out of a 1LE car. Not that it makes any difference: the parts are what they are, or aren't what they aren't, period, and retain no magic sprinkling of fairy dust or something based on whether some RPO that affected other parts of the vehicle was present or not.

3.45 was the "standard" ratio for G92 305 5-speed cars in 89. There are ALOT more of those in the world than there are 1LE cars in 88 and/or 89. Almost certainly that's what that rear came out of. A good find if that is in fact what it turns out that you've got (which you don't know for certain yet even if you think you do ), but not related to 1LE in any particular way.

I don't understand the attitude. I asked a simple question, in a reasonable manner.

Since you took that attitude, though, let me respond in kind, since, while you certainly seem to have a lot of good information, you also apparently lack even the most basic understanding of some fundamental concepts.

"3.45 gears" means their ratio is 3.45:1; the pinion will rotate 3.45 times for every rotation of the ring gear.

Since the wheels are directly connected to the brake rotor, which is directly connected to the axle, which is connected with tolerances of within a few thousandths of an inch to the carrier, which is directly connected to the ring gear, it is an absolute certainty that 1 turn of the wheel = 1 turn of the rotor = 1 turn of the axle = 1 turn of the carrier = 1 turn of the ring gear. Mre simply put, in my case, 1 turn of the rotor = 1 turn of the ring gear.

Since the yoke is directly connected to the pinion, it is absolutely certain that 1 rotation of the yoke = 1 rotation of the ring gear.

Given the ratio choices near 3.45 for this rearend (3.27, which would be just a touch more than 3 1/4 turns; 3.45, which would be just a touch under 3 1/2 turns, or 3.73; which would be just a touch under 3 3/4 turns, I can be certain that I have 3.45 gears, as I got just under 3 1/2 rotations.

Now, it might be a bit tougher to tell a 3.31 from a 3.42 in a 12 bolt, for example, using the method I employed (although I could, if I used a degree wheel, instead of my Mark I eyeball), given the available ratio choices, there is NO question.

And, when you rotate the pinion yoke with both wheels off the ground, both wheels (or rotors, in this case) will turn in the same direction. If it was an open differential, the wheels would have turned in opposite directions.

So yes, I DO know what I have; at least, as far as gear ratio and it's being a posi is concerned.

Pithy comments aside, the information you provided was very helpful. I'd be a lot more thankful, however if you hadn't stuck the insults on as well.

Has political correctness gotten so bad nowadays, that truth is considered an "insult" to someone who is mistaken? If so, I'm in some REAL trouble.

I'm not the one with the "my part is special" attitude, and inventing all sorts of reasons why, that have no basis in reality. To most people, thinking that one's part is "special" just because a similar part was used in some applications which are "special" even though the part itself is absolutely identical in every way, is "attitude"; not the act of explaining why it's not. It's kind of like the people who get convinced that their 882 heads are "better" than other 882 heads because they "came off of a Vette". As I said, the parts are what they are, no more and no less; they don't carry around some superior endowment of some mystical something that comes from some prior association. About the only magical property I can think of that comes that way, is the ability to lighten the next owner's wallet a little extra. That didn't by any chance happen here, did it? Like, the price wasn't by any chance higher because this was a "1LE" part, instead of merely a "Formula" part or whatever?

Is there a reason why you're not willing to take the cover off that rear and see what's REALLY inside there? To be honest with you, I'm QUITE familiar with how a rear end works, having rebuilt quite a number of them over the last few decades. But I'll also tell you, I'd be a VERY rich man indeed, if I had a dime for every person who was as totally convinced as you are (and with seeminlgy as good reasons as yours) from outside their rear end housing of what was inside it, only to find out that it wasn't what they thought it was. I'd strongly urge you to bypass trying to infer indirectly what those parts are, even though you think you have a handle on it; and proceed directly to observing the actual fact in question.

But that's all OK, no hard feelings or anything on this end; I'm glad I could bring a little truth and enlightenment your way, even if it hurt somehow or wasn't exactly what you were hoping to hear.