Beat up ol' K-10

M92PV4U

M92PV4U

Falling Down
Joined
May 19, 2020
Member Number
110
Messages
5,115
Loc
D.p. Ca.
I guess that the time has come to document the idiotic decisions that in a round about way lead to a truck capable of driving off road without a catastrophic failure every time :homer:.

The truck is a 1975 K-10 with a 454 th350 np203 10B 8lug front & 14BFF rear open diffs. It is currently sitting on a 4" lift that I plan on removing.

First project to tackle is the second ruined th350 by me:homer:.

Before you remove the transfer case drain the transmission fluid :homer:.
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I didn't learn my lesson and didn't drain the transmission even after making this mess.
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I was happy with the performance of harborfreight's scissor transmission jack. I have plans to trade this transmission core for another piece of this puzzle that I will go into later in this thread so I had to clean it up. La's totally awesome was my degreaser of choice, but my wife picked up the lighter version of it so I had to scrub extra hard. I ended up draining the fluid with a suction gun through the dip stick hole.
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I've already been discussing options for a replacement transmission model with total newb and he suggested a th400, out of my choices between a TH350 TH400 a SM465. For my use I agreed that the TH400 was probably the best option and I had a couple of them.
He set me up with an adapter to marry my spare np205 to the th400 and a few parts to complete the small bearing to big bearing conversion.
In the meantime I pulled a TH475 from a 1990 motorhome with 40923 miles (I'm already in possession of the 454) from that rv.
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This bitch weighs every bit of 200 pounds and kicked my ass getting it out of that hole.
These th475 or 3l80 hd starting in '90 have stright cut planetary gears that are louder and supposedly stronger than the helical cut gears of a th400 and they also have a deeper pan.

Fast forward to today and I got the parking brake and thil shaft extension removed and the transmission cleaned up, using the orginal La's totally awesome degreaser.
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The stick out on the rear shaft is 4½" so it should bolt to the np205 after modifying it to the big bearing & imput.

My plan is to maybe install a shift kit but otherwise leave everything as a "junk yard" transmission and even reuse the torque converter. I'll need to pick up a flex plate since I apparently lost it or was never in possession of it. I'll also be replacing my user damaged transmission hard lines with some ebay ss flex lines.
 
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I found the or atleast a 454 flex plate ment to bolt to the six bolt big block converter.
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The flex plate currently bolted to the engine is a 400 sb flex plate to mate up to the th350 small block converter, this flex plate is dual pattern. The big block 454 and small block 400 are balanced the same from the factory so the flex plates are interchangeable.
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GM Goodwrench engine rebuild tag
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Where did you find that they are balanced the "same"

Cause they are both externaly balanced but there is a massive wieght and stroke difference from a 400sbc to a 454.

Either way i was gona tell you that you need to run that 454 with that flex plate BEFORE you put the trans on. Ive gotten to many stuipd vibrations from 454 **** to just run them.



AND WERES THE PINK SHOCK BOOTS!?
 
total newb said:
Where did you find that they are balanced the "same"
Click to expand...
From my dad's friend that knows everything about chevys like you do. I've had three different ones on two different 454s on flex plate was directly off of my 400 small block. Both 454s ran smoothly.

The pink shock boots are coming after I remove the lift I'm going to run 32-33" x 10.50 tires and I'm going to replace the shovks.
 
Got ya, 70mph and TH400, 4.10s with 33s looks to be just shy of 3100rpm@70. 35s drops it by about 200rpm and dropping to 65mph does another 200rpm
 
Easy to find for sure. I know i have said it before but I like the 255\80R17s but not much choice and $. The 18-20" stuff seems easy to find used if you are just looking for something to put miles on.
 
So here's another piece of this puzzle.
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Hopefully I can figure out how to make this brake adapt to my np205... I'm missing a few parts but they look available.
 
M92PV4U said:
So here's another piece of this puzzle.
1000058600.jpg

Hopefully I can figure out how to make this brake adapt to my np205... I'm missing a few parts but they look available.
Click to expand...
NP200? I know on one of the M715 forums there was some detailed posts about converting those to a 205
 
posford said:
NP200? I know on one of the M715 forums there was some detailed posts about converting those to a 205
Click to expand...
200s are basicaly a 205 but with a offset rear output. Many of the parts even intercange.

mud tards like them because they are about as strong as 205 but offer the ability to get the outputs lower.

6x6 guys like to mix the 200 and 205 to get 2 rear outputs and build on rear axle offset to match up. I had a 200 years ago and sold it to a guy doing exactly that.
 
total newb said:
200s are basicaly a 205 but with a offset rear output. Many of the parts even intercange.

mud tards like them because they are about as strong as 205 but offer the ability to get the outputs lower.

6x6 guys like to mix the 200 and 205 to get 2 rear outputs and build on rear axle offset to match up. I had a 200 years ago and sold it to a guy doing exactly that.
Click to expand...
Yes I'm aware. I have M715s, I'm more familiar them than I'd like to be.
 
I've been lurking m715 zone, ck5 and a few others and have an idea of what needs to happen, but I'm not good at putting it all together in my head. Hopefully I'll get time this weekend to start tearing down and comparing parts.
 
I'm not a big fan of the looks but you can't deny they work good. Just need to swing them in when not towing a trailer and trying to look like the 70s equivalent of the bro dodges.

I can't for the life of me decide what mirrors to run on my 63 GMC. Thought about the westcoast Jr's that came with it but I'm not a fan of them, then my 99 Express has the same type as OP in good shape. I've seen a ton of them with the universal 80s GM style or 90s ford.
 
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