Hey guys, I have an 88 IROC with a blown motor and I have been contemplating looking for a 94-95 LT1 to swap in. I am pretty sure that my car has the 2.73 geared rearend with no Posi. I could not read the stamping on my rearend because it is worn off, but when I used to tromp on the gas, I would only leave one tire mark of rubber on the ground. That is how I figured out the car must be minus Posi.
Anyway, I was just wondering if I can swap an LT1 in my car without Posi traction, or am I going to have to invest in a new rearend as well? Any info would be fantastic.
Thanks guys,
JCRULZ

 

yeah, no reason you couldn't. just not going to have the performance it would otherwise with a better rear and ratio

 

Oh cool. My rear end isn't going to last that much longer anyway, I can tell by the way it bumps around back there. I'd like to score a Dana-wannabe rear end of some sort that has a REAL gear ratio. Not this rinky dink 2.73 non-posi gas saving hippie crap rear end. Why would anyone purchasing the top model of a sports car opt up for the 350 engine and then opt down for the 2.73 non-posi gears anyway? If the original owner was trying to save gas, why didn't he get the 305 or even a V-6 S/C? It's a mystery I will never figure out.
JCRULZ

 

It wasn't the person who bought the car, it was GM that put the 2.73 and 3.23's in the L98 cars to keep the fuel milage in line with what the government wanted it to be at the time.

 

Yeah, I knew about that, but I thought as the buyer you had the opportunity to choose from the different rear end options available. You could either have 2.77 non-posi (not 2.73 sorry that was for the vert) with limited slip, or opt up for the performance ratio rear end upgrade which gave the IROC coupe 3.27 ratio with posi. I wish the dude hadn't kept the standard option and had opted up. I mean opted up for everything else performance wise! I just gathered my info from this 1988 Camaro Spec guide I got from GM.
JCRULZ

 

Most people buy off the lot with little opportunity to pick and choose on such details. If its any consolation, the higher the ratio (lower numbers), the stronger it is. Just not as much fun.

 

Yeah, I think my rear end may be going anyway, so when it does the fun will begin!! I'd like to find a Dana-wannabe rearend (I know that Dana doesn't make rear ends anymore). I have heard there are a bunch of companies that make rear ends modeled after the Dana style. That will be my next major project most likely after I get her engine going again.
JCRULZ

 

If the car has the 2.77 in it, then that's the 9 bolt rear, I'm pretty sure all of them came with posi but could be mistaken.

 

I thought perhaps that I might have a 2.73 ratio at first. So I went and did some research. I have this collection of documents from GM talking about all the available options of each part of the 1988 Camaro. I thought my car had 2.73 gears originally, but I saw something that said that the lowest option for the non-convertible IROC-Z rear end was 2.77 gears with limited slip and no posi. It said the lowest gear ratio for the convertible IROC-Z rear end was 2.73 with limited slip and no posi. Man, I am so confused as to what gears I actually have, I spent a good 15-30 minutes under my car one day trying to find the stamp that tells what model rear end I have. It was so worn down somehow that I couldn't read it.
JCRULZ

 

Count the bolts on the cover, a rough way to see what it is....turn the wheel one turn, count the number of turns the driveshaft turns using a fixed point on the rear and the u-joint. 2 3/4 turns could be a 2.77, 3 1/4 turns a 3.23. Just a rough way of telling, and is pretty accurate.