casting # on 8 3/4 rear

[tim]

Hi guys. I have 3.91,s in one gear set with a casting # of 741, Iam looking to buy a bearing kit fot it. My parts man can get me a kit for casting # 742. Will this kit work even though my poinion shaft is 1 3/8. I took the small pinion bearing off, will I be able to order a kit by using that part #. Your replys would be appreciated. Thanks. Tim




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[V10nacuda]

TIM,
No parts are availble for that casting#. The only way to get parts would be NOS
Sorry for the bad news
V10

[Christopher]

My suggestion would be to take the numbers off of the bearings and races then go to a reputable parts house in your area and have them cross match the numbers.Some cities have warehouses that carry just bearings and seals.The best thing to do is use the numbers,not the application.A good example of this is that the 9" Ford and the 8 3/4 Mopar rear use 2 bearings that are exactly the same.

[tim]

Thanks guys. I will take whole rearend apart and try to cross reference the #. What is it with the 741 casting, is it older ? or is it stronger or weaker than 742 and 489 casting. Which rearend is better, as I have 3.23,s open in casting 489, and 3.55,s suregrip in casting # 489 and these 3.91,s suregrip in casting # 741. Thanks again guys. This site is great aye.

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[Old hippie]

741 case is the weakest due to (you guessed it) the small dia. pinion shaft. Stock for stock the 742 and 489 cases can be a wash. While the 489 case uses the 1 7/8 tapered pinion it also uses a crush sleeve to set the pinion depth, where the 742 case 1 3/4 pinion shaft uses a spacer/shim package to set the depth. I have had some real bad (read expensive) experiences with crush sleeves so always convert my 489 case rears to the Rateck spacer/shim kit. The 741 case is older, I do not think it has been used since the middle 60s.

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The Old Hippie Hisself
Ohippier@aol.com

[tim]

Thanks oldhippie. Do you think 741 case is too weak. I have over 400 horsepower with 340 73 Barracuda. I would think universal would give me a headache first, do you even recommend I use the 741. Thanks tim

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[V10nacuda]

Tim,
If this is an automatic you should be OK. If it is a stick with street tires & driving probably ok. Stick car with slicks...Questionable.
FYI, My 440ci 71 Gran Cp Barracuda weighs 3900# with me in it. On the dyno it was 450hp at the flywheel. I used a 741 case for 2 years with slick with no problem. The sure grip wore out, but I'm going to mill the side gears & try it in a similar powered duster.

Good luck
V10

[tim]

Thanks V10nacuda. It is a 727 auto, so I will try and cross reference #,s and rebuild it. It would be a shame not to really try out the 3.91,s as they were only in for one day and the car really performed well. I,m just getting used to new power and I think it,s gonna be a very interesting summer. Thanks again. Tim

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[Joecuda]

Hey Tim! Just a question.. I am building up a small block and I am at the stage where I am sorting in my mind what I will do with it. Can you tell me the specs on yours. You said it made 400 hp. Thanks. Joseph Tonna My email: hobbes@sonic.net

[This message has been edited by Joecuda (edited March 19, 2000).]

[tim]

Hello Joecuda, I have emailed some answers for you , it is titled 340 build up and it is under my wifes name Linda. Somethings I can control (car) and somethings I can,t (wife). Hope info helps. tim

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[Diplomat360]

Tim!

I just did what you are trying to do with the 741 case. I have all the TIMKEN part numbers you are looking for, even the prices if you need to see them (that is $CDN$). The parts are still all available, it's the crown and pinion gears that you won't find.

Email me : dariusz@mnsi.net and I'll forward the whole list to you...I'm at work now and don't have anything with me.

BTW: If you don't mind I'd also like to see how you built your small block, doing a 360 myself right now...expect around 400 hp as well. Thanks.