I'm looking for someone knowledgeable with the Ford 9" Carrier? My spider gears are severely worn. Surprisingly, to me, they are hard to come by. Autozone don't even list them. I can only get them from Advance Auto, by mail only. And there is only 1 listing on Ebay. Anyway, I found a used set on Ebay from a guy in Allentown, PA., who sells a lot of used Ford drivetrain parts. Mine is a standard open 2 pinion, his is a standard open 4 pinion. Both are 31 spline. He said the extra gears, and extra pins, make it stronger and it keels your gears from walking in side the carrier. He also said that I can take the new ring and pinion gear, and the new bearing set, that I just had installed on my carrier last month, back off of my 2 pinion carrier and install them on his 4 pinion carrier. Is this true? And in someones opinion, will there be any difference in fuel mileage?

 

28 or 31 spline axleshafts have nothing to do with spider gears (4215), only the differential gears (4236) are specific to one or the other.

C9AZ-4215-A .. 9" Spider Gear Kit / 1969/86 all with 2 (1 kit required) pinion carrier or 4 (2 kits required) pinion carrier / Obsolete

MILLER OBSOLETE PARTS in Binghamton NY has 4 = 607-722-5371.

GREEN SALES CO. in Cincinnati OH has 5 = 800-543-4959.

CARPENTER NOS OBSOLETE PARTS in Concord NC has 36 = 800-476-9653.

Left (upper) 9 inch / Right: 9" parts list #88 (28 spline) / Left (lower) 9" parts list #91 (31 spline).

Both parts lists: C9AZ-4215-A

 

If you want to go aftermarket LMC, as much as I don't care for them, has them.
Item #45-1945 $99.95
This is a kit that includes the spider gears, axle side gears, pin and thrust washers.
Truck Parts and Truck Accessories

 

I do understand that the difference between the 28 and 31 spline is referenced to the differential side gears. But, the new kits that
I have found, have specified 28 or 31 spline, because they also come with new differential gears. My carrier, as I mentioned earlier, is a 2 pinion. I purchased a 4 pinion, used, because I was told that it was a tighter, stronger system, that keeled the gears from walking, inside the carrier. I wasn't questioning the 28 or 31 spline, I was questioning whether my new ring gear on my 2 pinion carrier, would fit on the used 4 pinion carrier, that I ordered?

 

Thanks Mike. I didn't even think of looking there. But, I purchased a used 4 pinion carrier, that I am hoping that my new ring gear (that I had put on my 2 pinion carrier last month) will fit on. I was told by the seller that I could take the ring gear off of my 2 pinion, and put it on his 4 pinion. That is what I was questioning. It may just turn out that I'll have to get that set from LMC. But, I am glad you mentioned LMC. I have another question. LMC lists inner side panels for the 6' truck bed (which is what I have), but, they only list outer panels for the 8' bed. Any idea why? My thought is that, maybe, you have to buy the 8' and cut it down to 6'.

 

As far as I know, no one reproduces the short bed outer quarter panels. If you look at the price of the inners, it looks like the short beds are NOS and the long beds are Chinese repro's (if the shorts ARE repro's, then that price is a REAL ripoff!)
You can cut down the long bed outers to fit the short bed and there have been some threads here devoted to doing that.
On the aftermarket panels, I've heard mixed reviews on the quality, fit and finish of them. LMC's panels are usually on the poor fit and finish side.