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Discussion Starter · #1 ·
I read that an np208 will bolt in place of an np231c (chevy s10). does this mean my np231c can bolt in place of a 208? I am wondering this because i would like to switch to a manual transmission with a low 1st gear without spending a lot of money on adaprtors. I am thinking an sm465 with a 208 out of an 80s chevy would be a good swap since my 700r4 is starting to go and id like a manual tranny. Just wondering if i can put my 231 in place of the 208. thanks in advance
 

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Nope. The SM465 is 32-spline. The 208 or 241 that fits it has a 6-bolt pattern.

The S-10 NP231 is 27-spline, and has a 5-bolt pattern.

The closest you can get to what you want is a SM465/NP241 combo from an 88-91 fullsize IFS truck.
 

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Discussion Starter · #3 ·
what about an SM420? is that 32 spline output as well? i dont want to have to pay like 500 for an adaptor when i can get an another 700r4 around here cheap and throw a manual shift valve body in it.
 

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Dirty S10 said:
what about an SM420? is that 32 spline output as well?
10-spline... but a different bolt pattern, so the old SM465 (80-older) adapters won't mate up.

Only married SM420 application is with a pass. drop Rockwell T-221(?) for one year only ('67).
 

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i believe the sm465, that came married to an np 208 was a 10 spline too wasnt it? ill double check i have two of those sitting in the garage, they were out of 80s have ton chevys, im almost positive they are 10 spline 465s.
 

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Check again.

They're 10-spline for '80-older (205, 203, Rockwell). 1-tons carried it on thru '84.

'81-up is 32-spline (208 & 241). 1-tons didn't follow suit until '85.

Of course, the SM465/205 combo is a common swap to beef up the '81+ trucks.
 

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Discussion Starter · #7 ·
205 is a littler overkill for my application plus i like my 2.72:1 low range in the 231, i have a sye already, plus my front axle is a customized hp44 for my application. i guess there is no easy way to get a 4 speed with a low 1st gear in my truck. guess it is back to the drawing board.

maybe dual 231s like a i have read about and keep the auto who knows
 

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The SM465/NP241 is do-able. It is driver's drop and 2.7:1 also. Not too hard to find either as lots of the 88-91 fullsize stuff is reaching beater status. ;)
 

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Discussion Starter · #9 ·
cool i did not know that trucks that new had a 465 in them. was that an optional transmission or was it the factory standard 4 speed. In other words how common is it?
 

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For those 88-91 trucks...

SM465 is the base transmission on models with 8-lug wheels. In '91, the NV4500 was either optional for this first year, or they changed over mid-year.
 
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