im trying to start the modding process of my 89 rs 305 tbi and someone told me the stock gears are suckiN*SS
so the best recommendations i found were for 3.73 out of an l69 or iron duke
there are none of those at my junkyard
this is why i was wondering bout the 4th gen.
also any one have any mod/tips for a 305 tbi? STOCK STICK SHIFT

 

Have you already determined what gears you have in the car now? Check the RPO codes. If a gear change is in order then you'll want to make sure that the donar and your car are both equipped with the same carrier number, ie. 2 or 3. Again, de-coding your RPO code will tell you.

If the RPO codes are missing under the center console check the rear storage
compartment.

If all the RPO codes are missing, you can find the stamped numbers on the axle housing a few inches from the center carrier. You'll have to de-code those too. Hey, there might even be a tag on the center carrier? If all else fails, pry off the rear housing and find the stamped numbers on the ring gear. Once you have those, same as above, try a search or look in your manual for the gear ratio.

It's important to do these things before swapping the gear sets.

Good luck

 

The gears or the complete rear end from a 4th gen will fit your car. The rear end will be wider, but it will work.

 

it says on the 89 camaro specs on this website that manual came with 3.08
also is their any modification i will have to when getting a rear end from the 4th gen
can i take it to my mechanic and he should have no problems installing it?

 

Bolt-in, however there are other issues to consider apart from the rear end itself:

https://www.thirdgen.org/forums/tran...-10-bolts.html

JamesC

 

The rear end will bolt in if you use the complete rear end. If you want to take the gears out of it and use them in your rear end then there will be some problems. First of all you will have a 2 series differential with the 3.08 gears, and the 3.73 requires a 3 series. You won't be able to use the diferential out of the 4th gen rear end because it has 28 spline axles and your rear end probably has 26 spline axles. The axles will not interchange because they are not the same length.