I'm looking for a replacement diff, and there are different part numbers for the following years:

41200-PCZ-A51 - 2006-2009 + CR
41200-PCZ-A01 - 2004-2005
41200-PCZ-023 - 2003
41200-PCZ-003 - 2000-2002

It looks like the 04-05 diff has a breather valve, while the 06+ does not.

06-09:


04-05:


I'm looking for a replacement diff for a MY08. Can I use any year diff or does it have to be from a 06-09 car? I realize that there are probably not too many people that have replaced a diff on a 06-09...

It seems that the internals of the diff are identical throughout all the years, so I may need to build a diff using my original housing with internals from another one instead of doing a straight swap?

 

Per Puddydad:

 

What is the "tell" between AP1 and AP2 diff assemblies? I'm sure they're interchangeable, as my 05 AP2 was purchased with an AP1 diff w/4.77 gears in it. I just changed my diff to a used stock supposed AP2 unit, and while I didn't inspect the diffs very thoroughly, I couldn't see any glaring differences. I'll post some pics of the supposed AP2 unit when I get home if anyone cares to see them.

What happened to yours BTW? How bad is it?

 

I'm not sure; they look identical as far as part diagrams show. Only the part numbers are different.

I'm not 100% sure as I haven't opened it up, but I think I broke a tooth on part #9. The car is driveable and moves, but with a very rapid rhythmic clunk that is linear with vehicle speed.

I thought I heard a faint gear whine under load last weekend when I was coming from Laguna, but it was so quiet that I could only hear it with earplugs on (eliminates ambient noise). It was only audible after the car had plenty of time to warm up; I couldn't hear it around town.

I got a very loud whine on track during a cooldown lap, and I coasted into the pits. The clunking was present when I moved the car after letting it cool for an hour or so.

 

Difference is only on the driveshaft yoke. All AP1's use a smaller bolt hole than the AP2. There are some minor differences in crush collars and housings, but you can't tell that from the outside. Only difference for plug and play are the 6 bolt holes on driveshaft yoke.

 

My AP1 diff was making a whine-ering? noise under load for as long as I've owned the car, during the very first track day that I started to feel comfortable pushing the car it began spitting diff fluid all over everything, and the noise got noticeably louder, to the point where I was just hoping it would make it home. I really hope this stock AP2 diff holds up, I can't tell if it's making any untoward sounds because I installed a J's Racing 70RR pipe at the same time.
Doing my Tinnitus no favors.

 

So is this an AP2 diff?

 

Looks like it from Mikes part #'s he has listed in the first post.

 

 

I realize that this is the prop shaft, but it bolts to the differential at the companion flange (yoke) (#1 in pic above). These are the bolts that are different on the AP1 vs. AP2 differential.


BOLT, SOCKET (8X65) - 2001 Honda S2000 (90183-S2A-000) can be found as reference #5 in illustration

BOLT, SOCKET (10X62) - 2008 Honda S2000 (90182-S2A-A00) can be found as reference #4 in illustration


AP1 is first pic and uses a 8mm bolt. AP2 is second pic and uses a 10mm bolt