jsut curious, seems like alot of people swap out their stock rears with 4th gen rears and buy spacers for the front and then have to run 4th gen wheels. is it possible to take the posi unit and ring and pinion gears out of a 4th gen and put them into my third gen rear???

 

yes

 

i'm perfectly happy with my stock wheels and drum brakes. i want to swap my 2.73's for 3.42's and posi. seems like i can get a 4th gen posi/gears for alot cheaper than aftermarket. whats involved in changing gears and installing posi unit? what do i need to do to get my speedo to work correctly after gear swap? i have a 91 rs, don't know if you need it.

 

i have a 10 bolt. how many spling axle do i have? what size axle housing? its a 91 rs. with a 305tbi and 700r4 tranny.

 

you should have 28 spline axles (same as a 4th gen).
Rear end is 7.5"
Gears in the trans and sender need to be changed for the gear ratio you install in the car.

 

i just tried to swap the center chunk out of a 4th gen into my 88. the axles out of the fourth gen are too long and the center chunk is near impossible to spin when bolted up. did i get screwed when i bought the setup or am i missing something?

 

For one you did not do any reseach before you bought it.
1) the Axle shafts from the 4th gen rear are longer by 2" per side.
2) the center section will only accept 28 spline axle shafts (your 88 axle shafts are 26 splines).
You screwed yourself.

 

i knew the splines were different. no i did not do enough research. yes i screwed myself. didnt take long to put it back stock though.

 

possible for me to swap out posi and ring and pinion gears from a 4th gen into my 91 rs?

 

yes

 

so can i get a set of 28 spline axles out of a 90-92 and use the 4th gen center chunk? can i use my old ring and pinion or do i have to use 4th gen ring and pinion?

 

yes to the axles and yes to the gears if they are the same series.
3.08 and numerically lower are 2 series.
3.23 and numerically higher is 3 series.

 

is there any way to swap the spider gears to make the posi diff accept my 26 spline axles?

 

Like RS, i'm planning to swap the rear on mine. I'm guessing he has drum brakes (RS), wouldn't it be better and easyer to recommend a complete axle swap (this avoids the problems involved with setting up the gears..shimming...).

I was pricing out some used 4th gen rearends (disc, posi) for my car, $300 - $400 for grade "A" ready to bolt in rear ends.

www.car-part.com

I recommend, SEARCH BY DISTANCE, and put in your zip. It is common for most places to ship items.

 

i don't want to have to fab my own brake lines. but if doing a complete rear swap is easier than thats what i'll do

 

Flaring brake line is much easyier then messing with a 50lb chunk of steel. Plus if you don't get the brake line right the first time, it leaks...if you don't get your rear end right the first time, um you don't want to go there.

 

Ok, you all are very clever... now I ask!
I have my stock 15" five spock wheels on my 92 RS Stock drum rearend, I'm about to buy a 93 rearend with disc brakes, do my 15" wheels fit with those calipers, I mean the inside diameter of the wheel is bigger than the outer edge of the caliper on the 93 rearend? how about clearance?
I'll wait for your answer to buy it...
Thanks!

 

I'm planning to swap out the stock 3:08 3rd gen. 10 bolt with a 3:42 4th gen posi/disc rearend. I have a set of 17" X 8" 1985 era replica wheels on a 5 speed '91 RS .

Will there be problems?

Do they still use color coded speedometer gears?

Anyone know what color or what number is needed when changing from a 3:08 to a 3:42?