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Please help with 73 Riv diff questions

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Mark Drewett

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1973 Riviera
Hi all, first time on any forum so be patient with me please. I am in Australia and have a 73 Riviera with 66k miles that i am resto modding. I am having immense problems with the differential. There is so little information and its frustrating. My diff is very odd ball. What i am trying to do is find the correct part numbers including... Eaton True Trac. 3.9 gears to suit. 12 bolt hat to suit with cap tensioners. custom strange axles (bearings and retainers are not listed on strange order sheet). I think but not sure if the 73 has the 12 bolt truck diff as i purchased all above and none fit. The car True Trac is too narrow. Mine is 220mm wide from o.d brg to brg (approximately 9"). My original axles are 31 spline. Diff hat for car is way smaller. Mine measures 275mm (11") centre to centre of across middle bolt holes. My diff hat does not look same as truck hat (see pic attached). Pinion inner bearing id measures 1.865". Axles did NOT have c clips. My diff is an open wheeler, not a factory posi and has a tall ratio i think around 2.7 or 2.9 maybe. Diff hat.jpg Diff hat.jpg 20 inch foose rear.jpg One other thing. When we pulled the axles, one had a slight bend, and the axle bearing are different to each other. one is a tapered and one is square. Could the original have been damaged and the whole differential swapped out for some weird diff??? Any how i would really appreciate any input. Thanks, Mark.
 

Sal Collaziano

Buick: World Class Luxury
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LARRY70GS

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98 Riviera, 70 GS455 Stg1
Mel beat me to it:)(y)

There is very little aftermarket support for that rear. No new posi or gears available. That is the bad news. The good news is that rear is very sturdy with bolt in axles. Read the thread Mel linked for you. That thread is on V8buick.com. You need to go over there and join. It is hands down the best Buick site for 60 and 70's Buick cars. If you want gears and Posi, you need to find used parts. If you want, you can call Jim on www.jdrace.com. He may be able to help with parts, or have a line on them.

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Mark Drewett

New member
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1
3
Buick Ownership
1973 Riviera
Hi Mel and Larry, you guys are the best. Well it looks like i have a bunch of new 12 bolt parts for sale lol. Eaton True Trac, 3.9 Motive gears, Perfect launch hat, and a Timken brg kit. Thank God i was about to order custom axles tomorrow. As much as i appreciate the offer of help with more parts, i think its time to bite the bullet and do the 9" thing. I already have an LS1 and 4L60e in the car (sorry i know you guys are likely purists). Now if you guys are still with me, can you help me with a question regarding the front A arms. QA1 have told me they think, but not certain the front upper and lower control arms are same as 80-96 impala. Also is the 1973 Riviera a "B" body?
Thanks again for your help and i will from time to time post some pics of my progress. I hope i can do you guys proud with my project.
p.s i have made my own fibreglass split front bumpers and glass rear. They are a tad lighter than the railway iron originals. Also just finished making my custom centre console... console 16.jpg console 17.jpg front glass bumper.jpg line_1552011221237.jpg 20181222_173907.jpg alt and ac air intake.jpg console 16.jpg console 17.jpg front glass bumper.jpg line_1552011221237.jpg 20181222_173907.jpg
Thanks,
Mark.
 

Mark Drewett

New member
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1
3
Buick Ownership
1973 Riviera
Ok, Thanks Larry. Sorry to be a pest but not easy for this info here in Australia.
 
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Sal Collaziano

Buick: World Class Luxury
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Royal Palm Beach, Florida, United States
Buick Ownership
None right now
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