rear needed
- Thread starter franco
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moparkid1965
Active Member
I have one drum to drum no gears or 1 with 3.55 Mays Landing NJ
How about a 741 case, 3:91 Powerlock suregrip center section. Clean, nice gears and ready to pop in. $400.00 for that one. Or I have a 489 case, 3:23 Auburn style suregrip center section. $300.00 for that one. P.M. if you are interested. Geof
im not sure what you mean about these case sizes,im not at all up on rear ends and their compatibility.i have a 1970 duster with no rear end.i want a posi 3.75 to 3.90 gears,tell me about the 3.91 and is sure grip a posi?is the 741 case the 3rd member only ?if so what else would i need to get?thank you.dan
OK Dan, heres the scoop. I am referring to just the center section of the rear end, in this case the center section housing, gears and sure grip that install as a unit into an 8 3/4 axle tube housing. All 8 3/4 axle tube housings use the same center section regardless of whether it came out of an A, B, C, or E body, and of course some of the early to mid 70's trucks. When I referred to the number of the centersection housing, I assumed that you were familiar with their meaning. There are basically 3 different center section housing numbers that you find most of the time, a "741", "742" and a "489". That is just the last 3 digits of the part number. What that means to you is this. The 741 housing has a pinion gear shaft size of 1 3/8 diameter, the smallest of the 3 housings. They are found in most A-body factory performance applications and occasionally B-bodies but not very often. The 742 housing has a pinion gear shaft diameter of 1 3/4 inches and was found under most B and C body cars up until 69 when it was replaced by the 489, and the 489 has a 1 7/8 tapered shaft and bearing. Suregrip is to Chrysler products what Posi-traction is to GM products, a limited slip differential. There are 2 different suregrip units available in the 8 3/4 family. One is the "Powerlock" and the other is the "Auburn". The Powerlock suregrip unit has a series of clutches and discs in it that are replaceable when they get worn, thereby making the powerlock unit easily rebuildable. The Powerlock is sometimes referred as the clutchpack unit. The Auburn style is also referred to as the cone style as it has a cone type unit inside that acts as the clutches would in the powerlock. The Auburn style had long been thought to be unrebuildable once the cone wore out, especially if it scored the inside of the unit, but now there is a rebuild method for the Auburn. Either unit is interchangable into any 8 3/4 center section housing. So, the list of what you need to put an 8 3/4 rear into your car would be the correct length axle tube housing for an A body, the axles for the same housing, the center section or "PIG" ( short for Planetary/Interplanetary Gear), and the entire brake set-up with the same bolt pattern as the axles and wheels you intend to use. I have an 8 3/4 rear in every one of my cars and have used all of the different styles. I have burned off more than my share of tires and hard launches at the strip, and the 8 3/4 has held up to all the abuse a boy could give it. Plan on spending around $1000.00 to get the entire unit under there, between buying the items and having the brakes done and all. Incidentally, just in case you didn't know, 8 3/4 inches is the diameter of the ring gear, and the most common sizes are 2:76, 2:94, 3:23, 3:55, 3:91, and 4:10. There are other sizes available nowadays like the 3:73 aftermarket set from Richmond Gear, and some very high factory gears like 4:56 and higher, but they are usually reserved for just the strip. If you are buying gears for a center section housing that you have, you would need to know the last 3 digits of the housing, and get the correct pinion gear set for that housing. The entire part number is usually cast on the bottom of the housing just behind the driveshaft yoke on the drivers side. Sometimes you will find the early 60's housings with either no number or a different number than the usual 3 listed, but most of the time it is the common 3 housings. I hope all this helps and you get the set-up you want. Geof
Small Block
Well-Known Member
Good job Gig.
dmoore
NO IT'S NOT RESTORED
Hi Dan, its the center section complete, its the GOOD strong 489 case with Richmond 3.91 gears & a clutch style sure grip(just like original). Has the larger pinion yoke and 10 spline shaft. Im asking $600.00 shipped. Dave
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