Wanted to confirm some information on the 8 1/4 rear end (carrier swap)!

[Professor Fate]

Very surprised that Dr.Diff would say their is only 1 housing for the 8 1/4. 1973 thru 1975 used a carrier race that had a diameter of 2.891. 1976 and latter differentials used a carrier race diameter of 3.062. Some of the late 1975's had the larger size.

Changes were made over the years, but his assessment is accurate; inasmuch as in any given year/application there was only one housing, regardless of the gear ratio.
You can argue all the nuances: different housings for A bodies, B bodies, fullsize trucks, vans, Dakotas, Jeep XJs and Liberties, with and without snubber mounts, and on and on. But the pinion location never changed- that was his point.

 

[Fawkes]

Very surprised that Dr.Diff would say their is only 1 housing for the 8 1/4. 1973 thru 1975 used a carrier race that had a diameter of 2.891. 1976 and latter differentials used a carrier race diameter of 3.062. Some of the late 1975's had the larger size.

Correct, but that doesn't change the housing.

 

[townsend]

Lets ignore the discussion about the 2.45 carrier. We'll just cover the 2.71,3.21, etc. ratios. Try to picture the bare housing with only the carrier caps bolted to the housing. The bore size between the housing and cap is larger in 1976 and latter differentials. Doesn't that mean the housings must be different comparing early and late.

 

[Fawkes]

Lets ignore the discussion about the 2.45 carrier. We'll just cover the 2.71,3.21, etc. ratios. Try to picture the bare housing with only the carrier caps bolted to the housing. The bore size between the housing and cap is larger in 1976 and latter differentials. Doesn't that mean the housings must be different comparing early and late.

I totally see what you're saying. The bores for the carrier bearings are a different outside diameter. So although you can use a later carrier in an earlier housing, you need to use the appropriate bearings/races to marry the two, so I think we are in agreement there regarding the bearing O.D. change.

But the major confusion that im trying to address is that there is a "standard" and an "offset" housing. The The 8 1/4 thread argues that there is a special "offset" housing with the pinion located in a different arrangement made specifically for the 2.45 and higher gears and that you cannot swap gears into at all.

 

[townsend]

For that information, you can go to the Chrysler parts catalog for the answer. Pick any year the 2.45 ratio was available and you will see only one abodies axle housing listed for that particular year. Only the carrier changed.

 

[DionR]

All I have is my 73 8 1/4 under my 66 Plymouth Valiant to compare..
If I remember correctly the pinion is off set more then they othere, witch puts the ring gear closer to the housing, or farther away.. I couldn't put 3.55 in mine ... @halifaxhops

Sounds like you tired to use the same carrier your tall gears came with? The 2.45 carrier moved the ring gear over, but the pinion location didn't change. If you tried to bolt the 3.55 gears to that carrier, it would make sense that the gear might rub the case, but worse yet, even if it did spin it probably wouldn't ever get the back lash in spec anyways.

I wouldn't be that surprised if some of the confusion comes from people trying to swap gears using the wrong carrier, as there is definitely different ones of those. I could see buying a sure grip carrier from some guy at a swap meet that swore it came with 3.55 gears while it in fact was one for 2.45 gears. That gets plugged into a housing and won't work, so the assumption is that the housing is wrong and there must be different housings. Just a theory.

 

[Fawkes]

Sounds like you tired to use the same carrier your tall gears came with? The 2.45 carrier moved the ring gear over, but the pinion location didn't change. If you tried to bolt the 3.55 gears to that carrier, it would make sense that the gear might rub the case, but worse yet, even if it did spin it probably wouldn't ever get the back lash in spec anyways.

I wouldn't be that surprised if some of the confusion comes from people trying to swap gears using the wrong carrier, as there is definitely different ones of those. I could see buying a sure grip carrier from some guy at a swap meet that swore it came with 3.55 gears while it in fact was one for 2.45 gears. That gets plugged into a housing and won't work, so the assumption is that the housing is wrong and there must be different housings. Just a theory.

I agree with you 100%. That's why I plan to pull the parts myself so i know exactly what they came out of and why im trying to do so much research beforehand. Ive researched so much about 8.25's im about sick of them, lol