Toyota OEM V6 O2 sensors versus Denso, part number discrepancy.

I am trying to understand why the part numbers for OEM Downstream O2 sensors are different from Toyota, 89465-04340 (left) and 89465-04350 (right). They are both O2 sensors and according to @RockAuto website, the denso OE replacement is the same for both left and right downstream O2 sensors. The fact that there are different part numbers (and significant price difference) makes me think the downstream O2 sensors are uniquely different. Anyone have insight or experience with this? My searches got me nowhere.

I will probably do the AF sensors at the same time. I read that Denso is a good choice instead of OEM. I might go OEM if @gunny1005 can get me a good price. I don't want to start an anecdotal debate but facts/evidence always intrigues me.

Truck: 2010 Tacoma V6 AT 4x4 Access Cab

OEM Parts Numbers (local dealer prices):

89467-04040 - Left - Upstream (A/F) $149.29
89467-04050 - Right - Upstream (A/F) $149.29
89465-04340 - Left - Downstream (O2) $116.81
89465-04350 - Right - Downstream (O2) $130.06

Denso Part Numbers (Rock Auto):

234-9067 - Left - Upstream (A/F) $112.79
234-9084 - Right - Upstream (A/F) $112.79
234-4260 - Left/Right Downstream (O2) $47.79

 

The Toyota sensors may have different part numbers because of different length harnesses side to side.

Denso just made their harnesses the same length so they could consolidate, use the same part side to side and save money

Sometimes it's as simple as something like that. If either company says their part will work then you can trust them

 

denso makes them both so either is a good choice

 

That makes sense but I wouldn't expect the price difference to be $15 difference. But with OEM, the markups are insane.

I'll try to find pictures of each to confirm. Thank you for your suggestions.

 

I dont buy much toyota labeled parts. I get the oem supplyer for toyota. Spicer, denso, ect. It saves money for the same parts.

 

I bought those same sensors from Rock auto for my 4.0 with zero issues

 

OP - I spent some time on this same issue one day and ended up dizzy. I believe it's like b_r_o said. Denso simply used one length of line to save time/money.

 

I went with Densos from @RockAuto for the 4 sensors and MAF. Was about half the cost of the best OEM price I could find. The A/F sensors are nearly identical. The O2 sensors have different hole designs but I'm not concerned since it's downstream of the cat. MAF is identical.

At 85k my sensors looked bad. 1 AF sensor threads disintegrated when removing it. Truck has a lot of pep and the idle is now smooth. Not sure what helped since I also did plugs and a new air filter. Ill be doing sensors from now on at 75k if I can afford it.

Thanks for the advice and help!