What model transmission does my truck have
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CF Beginner
Joined: Jan 2024
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What model transmission does my truck have
Please help,
I'm getting conflicting information on which transmission is in my truck. But I need a new one.
1988 k1500 4x4 5.0l. 151k miles. Bare bones truck. No air, no power seats, locks, windows, etc. As far as I can tell the only option on this truck is 4wd.
I have an option to buy a TH400 (rebuilt). But the gentleman who I'm working with says I should have a 700r4.
This truck does NOT have overdrive, it is a 3 speed auto. That's why I'm looking at the TH400. Like I said bare bones. I'm not so young anymore but if I have to climb underneath for myself, what should I be looking at as far as bolt pattern, pan, etc to determine exactly which one I have.
Summer's hear and burning daylight, want to get this back on the road.
Appreciate any and all help.
If I do go with the 700r4 I'm guessing I'll also need to get new driveshaft???
Thanx so much
I'm getting conflicting information on which transmission is in my truck. But I need a new one.
1988 k1500 4x4 5.0l. 151k miles. Bare bones truck. No air, no power seats, locks, windows, etc. As far as I can tell the only option on this truck is 4wd.
I have an option to buy a TH400 (rebuilt). But the gentleman who I'm working with says I should have a 700r4.
This truck does NOT have overdrive, it is a 3 speed auto. That's why I'm looking at the TH400. Like I said bare bones. I'm not so young anymore but if I have to climb underneath for myself, what should I be looking at as far as bolt pattern, pan, etc to determine exactly which one I have.
Summer's hear and burning daylight, want to get this back on the road.
Appreciate any and all help.
If I do go with the 700r4 I'm guessing I'll also need to get new driveshaft???
Thanx so much
CF Pro Member
Joined: Mar 2024
Posts: 656
Likes: 96
From: Huntsville, AL
Everything I find online in a couple of searches says your friend is right - the 1988 K1500 most likely has the 700R4, which is a 4WD variant of the 4L60 transmission.
On my much newer (relatively!) 1996 C1500, there is a sticker on the inside of the glovebox door that has all the "RPO" codes for the vehicle as built. I think the code starting with an M, assuming that 1988 is consistent with 1996 through 2008 that I've had, tells you the transmission. You can decode the codes you find in the glovebox here:
https://decoderpo.com/
On my much newer (relatively!) 1996 C1500, there is a sticker on the inside of the glovebox door that has all the "RPO" codes for the vehicle as built. I think the code starting with an M, assuming that 1988 is consistent with 1996 through 2008 that I've had, tells you the transmission. You can decode the codes you find in the glovebox here:
https://decoderpo.com/
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botts2k6
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May 24, 2025 9:46 PM