ID rear end help

MaSnaka · #1 (**permalink**) 06-28-2007, 12:55 AM

I need help ID'ing this rear end. I know it's not a 9" or 8.8". If you can help me please do, Tag reads (top line)WDWU7GM,(bottom line)4L11 8521 B.

Thanks for your help. First time uploading pics...hope it works.
John

Jac Mac · #2 (**permalink**) 06-28-2007, 01:19 AM

8" as fitted to early Small Block Mustangs Fairlanes around 64 on. and also later "Fox'" Body Mustangs.

Still used 28 spline axles & Spider gears as 9" but otherwise R&P, Carrier, Pinion Brg Carrier, & Center section were all smaller than 9".

Hope someone can pin down model etc from Tag.

Jac Mac

Woodz428 · #3 (**permalink**) 06-28-2007, 06:34 AM

I'll get my tag book out later, but it is an 8" as pointed out. From the ribbing I would guess a later 60s model or after. If it hasn't been altered, the tag says that it is a 4:11 gear with a posi. That makes it something special, so probably a Mustang of some kind. It was never in Fox cars though, they used 7.5 and 8.8 with an intregal carrier...they were used in the Mustang II though.

Woodz428 · #4 (**permalink**) 06-28-2007, 07:38 AM

Haven't found that code yet, not the WDW part but the suffix code. I'll look at some other ones later. I came in to recheck the tag and it looks odd to me. It is larger than all the other tags I have (about a dozen) and the #'s are stamped with bigger #s as well. I'll continue checking but that oddity made me wonder about whether someone stamped it up. It is an 8", not in question, but a 4:11 gear would have had to be pre 73 or so because they stopped offering "good" gears about that time.

MaSnaka · #5 (**permalink**) 06-28-2007, 08:55 AM

I guess that's good news. I really don't know too much about these things. I do know that if it's posi, the posi isn't working, and if I have to break it down to fix it I'd like a little taller gear in there. Fwy rpm's are in the 3500-4200 range. Is it worth spending money on or would I be better off swapping it out? Thanks, John

Woodz428 · #6 (**permalink**) 06-28-2007, 11:49 AM

Personally, I'd keep it. I think it is as strong as the 8.8 and many parts are shared with the 9", it also has great parts availabilty too. The advantage of the 8.8 and one reason they went to them in almost all their vehicles is the pinion angle is better for economy ratings(read CAFE), but that translates into a little less strength.
That tag still is a little odd to me and if what is inside doesn't correspond with the tag it is either incorrect or a stamped one to indicate stuff that isn't present.

MaSnaka · #7 (**permalink**) 06-28-2007, 12:47 PM

Thanks Woodz, You too JAC. You tell me what I want to hear. What kind of shop do I go to to get the posi rebuilt? Transmission?
John

fsiewert · #8 (**permalink**) 07-20-2007, 02:37 PM

Me thinks that the only thing the 4.11 rear axel ratio came in was the 58-59 rancharo pickups. they too had 8" rears with posi and low gears.

fsiewert · #9 (**permalink**) 07-20-2007, 02:46 PM

I just discovered that I am probably talking out my tailpipe and had somthing else in mind...Like the 58-59 rancharo 9" being the same width as the 65-66 Mustang

DAVID GAGNARD · #10 (**permalink**) 07-20-2007, 03:21 PM

Yes, early (58-59) Rancheros had 9" rears in them, have one in my 65 Mustang Coupe road race car..........not sure of the years, but I think they all had a drain plug under the center till around 60 or 61........... they also are round on the back like a 8" rear, so, you have to look good and do some checking to make sure what it is......

Mine has the factory drain plug and it sure makes it easy to change the oil in the rear end.......and yes, they are the exact same width as the 65-66 Mustangs, even the spring perches are in the exact same location...........

I'm not sure from your pics just how many bolts hold the center section in, but I think the 9" rear has 10 bolts holding the center section to the rear end housing,just something else to check......

David