show me your rearend ... if it's a 8 3/4 mopar

Might want to check sales codes D56 and D91 for 73 A-bodies.
http://www.hamtramck-historical.com/

 

How did MOPAR identify the ratio in the 8.75 rear end. On the 9 inch ford there is a metal tag with the ratio on it bolted to the housing. What about the MOPAR 8.75?

 

Very early units had the ratio stamped into the bottom of the casting but by 1966 or so they used a small metal tag at one of the ten nuts that attach the center section to the housing.

 

here you go..........

 

You are absolutely correct. Sorry for the mis-information. For some reason I was crossing it in my mind with the Dana 44...the last rear end rebuild I was involved with.

Thanks for the clarification.

-Brad

 

Doing a third member change on the 8 3/4 in my Model A right now!!

It's out of a '66 Belvedere, if it matters.

 

Hate to dredge up an old thread, but my post about my 8 3/4 in the race car being just fine... well, it sure as hell aint now.

On a 1.44 60-foot @ 3100 lbs, I twisted the RH side of the housing 5 degrees, and bent the end of the axle on the RH side up and forward. It was nice leaving the starting line and seeing nothing but hood scoop and Jesus, but it sure was expensive. The 6.86 1/8 mile was on to being a 10.77 pass.

Going to a 9" over the winter. Anyone needing a bare 8 3/4 housing (I was keeping as a spare), a bare 489 pumpkin, and then my 4.57 geared 30 splined spool 489 pumpkin - its all for sale now.

Going 4.29 pro gear, 35 spline, daytona pinion, blah blah blah 9" ford blah blah blah.

 

Remember my comment about breaking stuff? Took a year to do it, but you got it broke. Funny you had to bend the housing before you broke the 8 3/4, then it sounds like you just messed up the axle, good luck with the 9". I'll bet when you bend that housing you won't blame the 9" though, don't forget to brace the 9" housing, sounds like you need it. Gene

 

I have used the 41 case many times. In fact I have one in my FED right now with 3.91 gears. I took it out of my MAX wedge car (426 Stg 111 MAX wedge with NASCAR rev 2 intake headers big cam Dynamic 3800 9.5" converter )where I beat on it unmercifully for almost 6 years. The only difference is the rear pinion bearing . The 41 is 1 3/8th, the 42 1 3/4s, the 89 1 7/8ths but you will not have problems with the rear bearing in any event. Bottom line is they all have the same flange and spline (either fine or coarse) and so the same diameter at the nut end. Since we know no part is strnger than its weakest point they all have the same chance. I know there is a lot said about the bearing size but it is mostly by those who live to have the biggest and best . If you have it you should use it . If it breaks then upgrade but if you are like me you will probably be getting a pension and have lost interest in cars by then. Remember the MAX wedge cars came with a 41 case. You dont read a lot about diff troubles with them. I even ran and still run the tapered keyed axles. I am driving 285 70R 15 BFGs with approx 490 to 500 hp so if the 41 stood this and it did then it is highly unlikey you will have any trouble at all in a street rod style car which is much lighter than my 63 Dodge 440 series hrdtp.
Just as an interest measure a 9 inch Ford pinion or even a Dana. Once you do that you will never worry about a 41 case again. I wouldnt hunt for one but if I had it i would and have used them without trouble. And I used them HARD. Back in the day we ran a lot of 440 bracket cars. We used to go to the wreckers and find a diff from an early 60s Dodge six cylinder 1/2 ton. Autos were typically 391s and standards were typically 410s We would change the ring gear over to the posi unit from the normal hi perf car. RR or Super Bee or Cuda for instance and would go bracket racing with slicks etc with these old 41 case sets. Never once not ever did we break a diff. At one pointI had 7 of these running out of my old POWER TUNE UP shop.We were running low 12s to mid elevens back then in our race cars.
Bin Da, getan das
Don

 

The 8 3/4 WAS backbraced. Didnt keep it from bending forward, and sure didnt prevent it from twisting. It'll meet a plasma cutter this winter, we're saving the ladder bar brackets and coilover mounts. I'll hang it on the wall as a testament to not doing it right enough the first time.

 

Someone brought back an old thread, and I can't resist posting this pic of the 8-3/4 in my OT beater...

3700# car with 1.7 sixty foot times. No transbrake, just my two feet.

Come out and see it at the Meltdown Drags this July

 

Did you see the new magazine project Demon with an 8.75 and a four-link setup, but not even braced? I bet it takes a dump quick if they put any serious steam to it.