Part Numbers for O2 Sensors

I need to replace both oxygen sensors on my '97 cherokee. from what i've seen on here, i should get the bosch replacements. i was just looking on summit racing and they didn't bring up a bosch sensor for the "rear." i have been looking around for a couple hours now and i keep coming up with different part numbers and different brands:brickwall Can someone tell me where i should buy them and what the numbers are for both sensors? I'd rather buy them online because the local shops want $70+ a piece. i dont mind paying the extra for the proper plugs either, i'd rather just plug it in and not worry about another connection/ point of failure.
Thanks a lot!:wave:

nobody knows the numbers for the o2 sensors?

Upstream 13100

Downstream 13138

what about these?

I only found one of the bosch's on summit and the other one was 70 bucks:doh:
I found these searching around and i was wondering if they're the right ones because they are pretty reasonably priced. is the low cost a reflection of quality?

I got both of mine from www.summitracing.com. Front O2 sensor #NGK-23099 for $45.39, and rear O2 sensor #NGK-23151 for $48.39. Shipping is free, but there is a $9.95 handling fee on the entire order.

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NGK is best known for their sparkplugs, but they probably make good O2 sensors also.

On the NGK website the front and rear sensors are the same part number (23121), which seems kinda weird seeing as every other website lists 2 different part numbers.

http://www.ngk.com/faqmain.asp