73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: got2haul on February 03, 2009, 08:34:03 am
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My '80 stepside has a 2-piece driveshaft with a carrier bearing. As I was looking over the 1980 SWB fleetside I just picked up I noticed that it has a 1-piece drive shaft, with no carrier bearing (obviously). Does anyone know or have a theory as to why GM did this -- same year, same wheelbase, different driveline?
There are differences in the driveline: the stepside has the 4-speed granny-low transmission (what's the nomenclature for this transmission -- model name/number, gear ratios?) while the fleetside has an automatic. Does this have anything to do with it?
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Cant help with the drive shafts but the tranny is a Muncie SM465
(http://www.novak-adapt.com/images/graphics/sm465_specs.gif)
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i dont know why they did that...but i have an 84 gmc c2500 3/4ton long bed with a th400 automatic tranny and it has a 2 piece drive shaft
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My '79 has a two-piece driveshaft as well. I heard they were standard on the "Big 10" and "Heavy Half" models, but I don't know if this is really true.
Smitty
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the majority of longbeds got 2 piece driveshafts but I have never seen a shortbed with one
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Confusing, my longbed 1/2 ton 1-piece and I have an 83' shortbed 1-piece. Both are 4x4 if that makes the difference. And the longbed has manual sm465 the shortbed is auto. Both have 208 transfercases.
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Does your Stepside have HD springs on it? 2 piece driveshafts were always put in HD trucks. The SM465 leads me to believe it is a HD truck.
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Does your Stepside have HD springs on it? 2 piece driveshafts were always put in HD trucks. The SM465 leads me to believe it is a HD truck.
Chris according to this site
http://www.novak-adapt.com/knowledge/sm465.htm
this tranny was used in light duty trucks. I trust your info more, what was more likely stock for a truck of that era ?
Btw dont play hero and try picking this tranny up by yourself if you want kids in the future :)
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It was used in light duty trucks all the way up to HD trucks. I was trying to say that our trucks have a HD package called Heavy Half in the early years and they generally had 2 piece driveshafts and 56" leafs.
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The RPO list that was in the glove box lists 1G50, "Heavy Duty Rear Springs." So maybe that's it?
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That is it...
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I had heard back in the day that GMC was always more HD than its counterpart. I know that the GMC 1/2 ton had leafs where the Chevy 1/2 ton had coils back in 72. Any truth to that?
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Not to steal the thread, but I just sold a 78 K-20 4x4 3/4 ton SM465/NP205 3.73 gear ff rear dana 44 front that had a 2 piece rear shaft. It too was optioned heavy, also with a factory tach... funny thing, that somehow found its way to my storage shelf before the truck left. ::)
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Two piece shafts allow for more clearance and reduced driveshaft diameter. One piece shafts, the longer they are the fatter they need to be. Is one better than the other? I'll let you know when I have one break into a million pieces. ;D
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To add to the confusion My 87 V30 (k30 in my mind) had a factory 454 TBI, turbo 400/205, and a Dana 60/14 bolt (3.73's) with a 1 piece driveshaft. I would have thought all 1 tons got the 2 piece shaft.
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It is not a "Heavy Half" thing to have 2 piece driveshaft. My 74 C10 350 Th350 12 bolt 2wd SWB with 56" 8 leaf rear springs has a one piece driveshaft. I would bet it has something to do with the manual transmission.
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maybe they just switched it up randomly so the assembly line workers didn't get bored... ;D
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my 79 was the olds diesel originally, it has a 2 piece driveshaft, it's a shortbed. the 80 i bought has a one piece, and when i swapped the chevy 350 over, of course the two piece didn't mate up, so the one piece outta the 80 had to come with it. or HAS to come with it, cuz i still didn't get that far.
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http://www.rodandcustommagazine.com/techarticles/0608rc_driveshaft_tech/index.html
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I didn't say ALL of them..
....HD package called Heavy Half in the early years and they generally had 2 piece driveshafts and 56" leafs.
Does the TH350 in question on the HD truck have a long tailshaft? Most trucks didn't get the long tails, they got medium tails. this will reduce the length of the driveshaft allowing a 1 piece to work. Not to mention we are talking about truck over 30 years old, how many are still in the same setup they were that long ago..
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I didn't say ALL of them..
....HD package called Heavy Half in the early years and they generally had 2 piece driveshafts and 56" leafs.
Does the TH350 in question on the HD truck have a long tailshaft? Most trucks didn't get the long tails, they got medium tails. this will reduce the length of the driveshaft allowing a 1 piece to work. Not to mention we are talking about truck over 30 years old, how many are still in the same setup they were that long ago..
I did not say that all of anything got or did not get a certain driveshaft, I was stating that my truck is a "Heavy Half" (it is on the RPO sheet) and does not have a 2 pieces driveshaft. It has no provisions for the crossmember for a carrier bearing and it was the original transmission to the truck. So in my opinion the 2 piece driveshaft is not necessarily part of the Big 10 or the Heavy Half package. I believe that to get the 2 pieces driveshaft it would take a HD 4 speed manual transmission. Your correct about the medium length TH350, I miss typed there.
maybe they just switched it up randomly so the assembly line workers didn't get bored... ;D
Naw cause then they would be Ford........ ;D
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It's not a manual transmission thing. They all have provisions for the crossmember. Most short tailshaft applications came with the two piece driveshaft. My 1974 C15 came stock with a 454, TH400 short shaft and two piece driveshaft with 3.73:1
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It's not a manual transmission thing. They all have provisions for the crossmember. Most short tailshaft applications came with the two piece driveshaft. My 1974 C15 came stock with a 454, TH400 short shaft and two piece driveshaft with 3.73:1
See that is strange because the short tailshaft TH400 is not much different in length than a medium tailshaft TH350 (or a 700r4). So it is not a transmission length issue, it must just be the vehicles have to be equiped in a certain manor......hmmm.
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Different model, wheelbase and driveline configuration dictated which truck came with a two piece. Most two piece have the slip yoke integrated while many one piece had no integral slip yoke.
It'd be nice if everyone could chime in with their specifications as long as it's the original driveline set up and maybe we can help identify which options were more poularly fitted with 2 piece shafts.
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Different model, wheelbase and driveline configuration dictated which truck came with a two piece. Most two piece have the slip yoke integrated while many one piece had no integral slip yoke.
It'd be nice if everyone could chime in with their specifications as long as it's the original driveline set up and maybe we can help identify which options were more poularly fitted with 2 piece shafts.
76 GMC C3500 350 SM465 has the two piece ;D
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1985 C10 LWB originally 4.3 v6 TH400 10 bolt with 2 piece Drive shaft.
only 3 leaf rear with overload so i believe its a LD setup.
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79 GMC stepside / shortbox. 350/400 2 piece.
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It seems like every factory TH400 set up I've seen or had came with a 2 piece. My 1980 had a one piece with a TH400 but I'm not too convinced it came that way since it was an original 5.7 Diesel truck.