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dagon dagon!
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I am so tired of my silverados being automatic... what is a good heavy duty 4 speed?
 

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gm's 465 tranny was likely the toughest tranny ever put in a pickup. you could find them in[ not exact on years span] 70's to early 90 gm 3/4 and one ton trucks. they will make a truck a real truck! this being said, i would also look into a nv4500, very similar tranny, just has the benifit of an od.. the 4500 will cost more coin however..
 

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Are you talking about for the 90 2500? A 465 would definately be the wany to go on a 4spd,in fact it's the only way to go. You will need an 81-91 with a 32spline rear output.
 

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the SM-420 4spd manual has been a tried and true design seem to do rather well in my truck i have towed loads as heavy 23K-LB's. . . tho my old GMC V-6 engine only makes [email protected] and [email protected] . .I do believe they also put this trans behind some of the stronger GMC V-6's. . .from 60-74. . .Ido believe this same trans went on to be used with 427's n 454's. . .

Mikey
 

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420's are great IMO too but I was under the impression parts are hard to get and they were only made 1 year to accept a married t-case and that was 1967. I had 2 at one time and sold both. The only t-case that will direct bolt to them is a 221 Rockwell and they have issues :fan.

the SM-420 4spd manual has been a tried and true design seem to do rather well in my truck i have towed loads as heavy 23K-LB's. . . tho my old GMC V-6 engine only makes [email protected] and [email protected] . .I do believe they also put this trans behind some of the stronger GMC V-6's. . .from 60-74. . .Ido believe this same trans went on to be used with 427's n 454's. . .

Mikey
 

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:bang Sorry i forgot to read the part about using it in a 4x4 sorry. . .

I have had great luck with mine i am just not sure how new they went but i had been told they were around for many years. 195?-198?-9?

Mines been towing heavy loads since 1962 with a 379M-V6 in front of it.
Them Big block V-6's don't seem to give up they just keep towing and towing. . .

Mike
 

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The SM420 was last ran in 67 in pickups and replaced by the SM465. Trucks I believe got the 465 around the same time.
 

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I don't know that very well could i was just told it was used in every 4spd manual unit from the mid to late 50's threw the 60's then was only in medium trucks for the 70s+ so i just guess on that ending year. . .

I have got say it is one of the smoothest shifting quitest running 4spd's i know of and tough to. . .

i had the truck about 2 years running the heck out of it when i desided to change the Gear lube in the trans n diff.

It poured out Rusty Brown and was only half full. i was a bit pissed i didn't check it sooner i had spent 2 years towing around 18-22K loads. . .

well it cleaned out after several short run drains and i had been running 80w-140 AMSOIL long life lube.

9 years of syn fluid and no leaks or drips. stays full and is always clean tho i change it every spring now i have just went to the SAE190 gear lube i can't wait to see how it looks this may and SAE250 in the Diff. . .

Mikey
 

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I agree with these people!

The SM465 is one of the best 4 speeds out there.Very popular in 2wd or 4wd applications also.Granny gear is something like 6.56:1 but the SM420 is 7.05:1 so it is lower for more pulling capacity.I've got a SM465 behind my 292 in-line six
and it's stout but slow.We're in the process of putting a SM465 behind a 350 ton chevy '73.It was automatic,I hate automatic trucks!!I believe only manual trans. should be offered in trucks especially if their diesel!! Jake
 
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