# 90-91 Distributor TD-23U / 24U difference??

**URL:** <https://forum.g2ic.com/t/90-91-distributor-td-23u-24u-difference/54899>\
**Category:** Stock Engine-Bay Components\
**Created:** [October 5, 2004, 3:03pm UTC](https://forum.g2ic.com/t/90-91-distributor-td-23u-24u-difference/54899 "2004-10-05T15:03:33Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![system](https://forum.g2ic.com/user_avatar/forum.g2ic.com/system/32/1_2.png) [@system](https://forum.g2ic.com/u/system)\
**Post date:** [October 5, 2004, 3:03pm UTC](https://forum.g2ic.com/t/90-91-distributor-td-23u-24u-difference/54899/1 "2004-10-05T15:03:33Z")

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I searched for TD-23U & Td-24U before posting…only found a WTB thread.

Does anyone know the difference between these? I’ve rebuilt a B18A composed of 2 junkyard motors, niether of which came with a distributor. It’s getting to be time for a dist. and I ran into this snag.

What’s the difference?  
I’m using a PR4-2 head (# cast above the #1 ex port) and a PR4-A10 ECU if it makes a difference.  
The head is definately a 90/91 head; A 90 if you can go by the other numbers on the EX side.

Thanks for any help.  
-TJ

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**Author:** ![Archon](https://forum.g2ic.com/letter_avatar_proxy/v4/letter/a/df705f/32.png) [@Archon](https://forum.g2ic.com/u/Archon)\
**Post date:** [October 5, 2004, 3:49pm UTC](https://forum.g2ic.com/t/90-91-distributor-td-23u-24u-difference/54899/2 "2004-10-05T15:49:27Z")

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The only wiring difference between 90 and 91 is the PA sensor.

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**Author:** ![system](https://forum.g2ic.com/user_avatar/forum.g2ic.com/system/32/1_2.png) [@system](https://forum.g2ic.com/u/system)\
**Post date:** [October 5, 2004, 4:06pm UTC](https://forum.g2ic.com/t/90-91-distributor-td-23u-24u-difference/54899/3 "2004-10-05T16:06:58Z")

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PA sensor…What’s different? Wire color/position?

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<div class="post-metadata">

**Author:** ![Archon](https://forum.g2ic.com/letter_avatar_proxy/v4/letter/a/df705f/32.png) [@Archon](https://forum.g2ic.com/u/Archon)\
**Post date:** [October 5, 2004, 4:09pm UTC](https://forum.g2ic.com/t/90-91-distributor-td-23u-24u-difference/54899/4 "2004-10-05T16:09:28Z")

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I did a little search for you and I think they are interchangeable.

[http://www.andale.com/stores/sf\_itemHome.jsp?foo=bar&sid=212250&cid=12633049&lid=100459079&mode=1&catId=1355352&parentCatId=1299368](http://www.andale.com/stores/sf_itemHome.jsp?foo=bar&sid=212250&cid=12633049&lid=100459079&mode=1&catId=1355352&parentCatId=1299368)

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<div class="post-metadata">

**Author:** ![system](https://forum.g2ic.com/user_avatar/forum.g2ic.com/system/32/1_2.png) [@system](https://forum.g2ic.com/u/system)\
**Post date:** [October 5, 2004, 4:16pm UTC](https://forum.g2ic.com/t/90-91-distributor-td-23u-24u-difference/54899/5 "2004-10-05T16:16:00Z")

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Yeah, that’s where I was going to get one & where I learned about the 2 different units…  
I didn’t bother reading this part until now though:  
\* This distributor is compatible with the following OEM housing #'s: TD-23U & TD-24U

Still curious what the difference is though.