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Are np203s now desirable? - full time 4x4

TJ1978 said:
Like I said earlier, too late to stop the purchase.

I have the 205, that's the direction I'm going tentatively. I've yet to read a negative in switching from a 203 to a 205. Had I seen or been made aware of the 208 option I may have considered it and left the 205 alone.

Even still, it's not in the truck yet so I could/can always sell it and snag a 208. This Tcase swap isn't something that's happening in the next month. 205's seem to be getting harder to find so I saw this one and snagged it up.... just in case.

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Keep the 205 don't worry about using it. I run my 205 in all different terrain. High speed to Moab. Are there better options....sure but it does well and like you said, you have it. Run it. No skid plate needed. :eek:
 
6872xtc said:
Careful! Your transmission may disagree at some point!
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I know right. The TH400 is holding up so far. It is my worry point though right now. Mainly because the rebuild was probably iffy. It's getting an 8L90 hopefully next month. It's taken 2 years of solid abuse so far.

Skid plates and sliders are on this years BB list.
Another wish list item...hint hint cough cough is an Ed Built Motorsports swing down tire carrier for a 37" @Fastereddie cough....cough...ehgmm
 
TJ1978 said:
Like I said earlier, too late to stop the purchase.

I have the 205, that's the direction I'm going tentatively. I've yet to read a negative in switching from a 203 to a 205. Had I seen or been made aware of the 208 option I may have considered it and left the 205 alone.

Even still, it's not in the truck yet so I could/can always sell it and snag a 208. This Tcase swap isn't something that's happening in the next month. 205's seem to be getting harder to find so I saw this one and snagged it up.... just in case.

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Looks like this np205 has seen better days. I would not run it with out opening it up and checking every thing out.
 
tarussell said:
Something to ponder - with the exception of the CUCV’s ( they needed the low range gear so Uncle Sam did what it took to get the contract ) a 208 was never an option in a civilian K-30 and there is a reason for that….
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True, but all high powered modern diesels are now sold with chain drive cases.

Martin
 
TJ1978 said:
Like I said earlier, too late to stop the purchase.

I have the 205, that's the direction I'm going tentatively. I've yet to read a negative in switching from a 203 to a 205. Had I seen or been made aware of the 208 option I may have considered it and left the 205 alone.
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I get that.

An NP205 is much better than an NP203.

The easiest and cheapest way to swap over to an NP205 is to find a 1980 parts rig. you end up with a slip yoke though.
 
82355 said:
True, but all high powered modern diesels are now sold with chain drive cases.

Martin
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Not slamming a chain driven case as being weak at all - just stating that a 208 was not equal in service duty factors between the two cases being discusse.

Cases like the 241HD’s and 271/273’s and Magna cases that came behind a lot of strong diesels also had better set of planetary gears, better chains and sprockets and much larger output shafts and bearings, plus the housings are stouter. The input torque rating differences between cases are another indicator of strength and intended use.
That being said, I actually like a 208 case in certain applications - I ran one in my old 85 K-5 with K-30 axles for a decade without a complaint. The 2.61:1 low range was great and the case was good enough for that rig so I never swapped it out even though I had several 205’s and related components available if needed.

Side note on the 1980 on up 205 slip yoke cases - if a slip yoke case is not desired the rear output shaft housing assembly can easily be swapped out for a bolt on yoke assembly,
And there were plenty of bolt on yoke 205’s made after 1980 - they came in trucks with a carrier bearing rear driveshaft set up like crew cabs and cab chassis K-30’s and V-3500’s all the way up to 1991 . Regular 131.5” wheel base trucks in the eighties used the slip yoke 205’s but the others did not - bolt on rear yoke cases are available after 1980.
 
tarussell said:
Not slamming a chain driven case as being weak at all - just stating that a 208 was not equal in service duty factors between the two cases being discusse.

Cases like the 241HD’s and 271/273’s and Magna cases that came behind a lot of strong diesels also had better set of planetary gears, better chains and sprockets and much larger output shafts and bearings, plus the housings are stouter. The input torque rating differences between cases are another indicator of strength and intended use.
That being said, I actually like a 208 case in certain applications - I ran one in my old 85 K-5 with K-30 axles for a decade without a complaint. The 2.61:1 low range was great and the case was good enough for that rig so I never swapped it out even though I had several 205’s and related components available if needed.

Side note on the 1980 on up 205 slip yoke cases - if a slip yoke case is not desired the rear output shaft housing assembly can easily be swapped out for a bolt on yoke assembly,
And there were plenty of bolt on yoke 205’s made after 1980 - they came in trucks with a carrier bearing rear driveshaft set up like crew cabs and cab chassis K-30’s and V-3500’s all the way up to 1991 . Regular 131.5” wheel base trucks in the eighties used the slip yoke 205’s but the others did not - bolt on rear yoke cases are available after 1980.
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Yep.

I should have been more specific, because he is working on a Blazer (I think), I was referring to a 1980 Blazer (or Jimmy), as that would make all of the parts a direct swap (including driveshafts). All 1980 Blazers and Jimmys have a rear slip yoke.

Martin
 
82355 said:
Yep.

I should have been more specific, because he is working on a Blazer (I think), I was referring to a 1980 Blazer (or Jimmy), as that would make all of the parts a direct swap (including driveshafts). All 1980 Blazers and Jimmys have a rear slip yoke.

Martin
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Yes, '78 blazer
 
82355 said:
Yep.

I should have been more specific, because he is working on a Blazer (I think), I was referring to a 1980 Blazer (or Jimmy), as that would make all of the parts a direct swap (including driveshafts). All 1980 Blazers and Jimmys have a rear slip yoke.

Martin
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That makes sense now
 
What would be helpful is a guide that has the drive shaft lengths at stock height for various years and tranny/tcase combinations for the K5 at stock hieght. I ended up getting new driveshafts made. I wonder what driveshafts would have been a direct fit.
 
tarussell said:
If you would like to use a side torque bar/brace ( like your TH350/203 had ) you could get a side brace/bar from a 81~84 K-30 that came with a 465/205 set up - same dimensions from attachment point on the 205 to the proper bell housing bolt location as your TH350/205 has.
If your 205 is not drilled the boss is there on all GM 205’s and can be drilled.
One of these bars is a great idea on any automatic trans but especially on an older thin casting TH350 case - use one if at all possible because they do a wonderful job of keeping everything in place and happy happy happy.

Just as a note: not all 205’s after 1980 came with a slip yoke rear output. The regular long bed fleetside 131.5” wheel base trucks did but any K-30 that came with a carrier bearing equipped rear driveshaft ( such as Crew Cabs, Cab Chassis ) came with a rear bolt on yoke.
Just did not want ya’ to skip over any potential purchases because ya thought all were a certain way after a time period.

As for your question about which front output to use and which is stronger - the square flange style fit a Saginaw style cv-joint and the output shaft is 30 spline while the yoke style front output was made for a Spicer style cv-joint and the output shaft was a course 10 spline that was slightly smaller in diameter than the 30 spline shaft.
The Saginaw style cv-joint does not have a lot of tolerance for more angle than OEM set up - could be ground and clearanced but life expectancy goes down.
The Spicer style cv-joint puts up with a little more angle as is.
As for the front output shaft size difference the 30 spline is stronger ( could also up grade to the 32 spline shaft too ) than the 10 spline shaft but if you are still running a 1310 series front driveshaft than don’t worry about the transfer case shaft breakage - most likely even the smaller 10 spline shaft will outlive a stock front driveshaft.
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Do you happen to have one?
I'll post a wanted thread if not..
 
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