Did any 3/4 tons get 14 bolt full floaters after 1981?

[thatK30guy]

Would axle code stampings tell what year and type axle it is ?..
My old GM parts manuals used to list them that way..(!946-72 catalog I have)..

Axle codes, or BOM (bill of materials), are sketchy at the most. While I'm not familiar with the specifics of the numbers/letters on BOM's it's the drivetrain shops that almost always ask or request of these digits when ordering the parts such as ring and pinions, etc., in order to get the correct parts. This leads me into thinking the BOM does identify WHAT the axle is but does NOT tell what ratio it has.

 

[bablazer73]

Do you have proof that they were factory? Not trying to call you out, just trying to find the answer.

Martin

I bought and drove the 82 3/4 ton 2by truck for a summer.
350/th400, 14ff.
All factory.
I used it for parts for a 85 3/4 ton 4x that had a Semifloater.
GM did use the FF, but was was in over 8,800 GVW trucks.
I had another mid 80’s 2x truck I cut up, and that had a FF too.

 

[MTBLAZER89]

GM documents starting in 1981 discuss the new rear semi float rear axle with a 6000 lb GAWR is standard on ALL C20/K20 trucks/burbs with the exception of C20 crew cab and 454 equipped trucks.
The vehicle information kits for 81+ C20/K20 GVWR lists the highest available rated 3/4 ton as 8600lbs and shows those rigs came with the 6000lb rear axle (semi float).

Basically using the factory documentation out there everything I have ever rear shows only 2wd 3/4 tons with a 454 got the FF. Everything else got the 9.5" SF rear axle.

 

[rksjd8420]

GM documents starting in 1981 discuss the new rear semi float rear axle with a 6000 lb GAWR is standard on ALL C20/K20 trucks/burbs with the exception of C20 crew cab and 454 equipped trucks.
The vehicle information kits for 81+ C20/K20 GVWR lists the highest available rated 3/4 ton as 8600lbs and shows those rigs came with the 6000lb rear axle (semi float).

Basically using the factory documentation out there everything I have ever rear shows only 2wd 3/4 tons with a 454 got the FF. Everything else got the 9.5" SF rear axle.

^^^^exactly. The difference in camper special or anything similar on a 3/4 ton was only a different in springs. Same rear axle.

3/4 ton gvwr was 8600 1 tons with a snow plow package or something similar got overloads and the 10,000 pound gvwr instead of 9200. Cab and chassis might be different. I know it was on later models and I am pretty sure I had a square body cab and chassis with a gvwr of about 12,000. CUCV M1028 and M1031 were something like 9800 or 9900 gvwr.

 

[6.2Blazer]

Take it for what it's worth but if you look up rear axle parts for a mid-80's Chevy K20 on any website it lists both the 9.5" and 10.5" rear axles as options.

 

[JoeliusZ28]

^^^^exactly. The difference in camper special or anything similar on a 3/4 ton was only a different in springs. Same rear axle.

3/4 ton gvwr was 8600 1 tons with a snow plow package or something similar got overloads and the 10,000 pound gvwr instead of 9200. Cab and chassis might be different. I know it was on later models and I am pretty sure I had a square body cab and chassis with a gvwr of about 12,000. CUCV M1028 and M1031 were something like 9800 or 9900 gvwr.

Do you know if there was a snow plow package available on a K20? My dad says my grandpa’s K20 had that but i didn't think such a thing ever existed.... ive never seen it on a SPID tag and it isnt in my 1984 brochure.

 

[JoeliusZ28]

I bought and drove the 82 3/4 ton 2by truck for a summer.
350/th400, 14ff.
All factory.
I used it for parts for a 85 3/4 ton 4x that had a Semifloater.
GM did use the FF, but was was in over 8,800 GVW trucks.
I had another mid 80’s 2x truck I cut up, and that had a FF too.

View attachment 310768

View attachment 310769

Unfortunately its well documented that 14FF’s came in 2wd’s so this is nothing surprising. It also muddies the waters a bit on this mystery since so many parts references include both lines of the trucks.

 

[rksjd8420]

Do you know if there was a snow plow package available on a K20? My dad says my grandpa’s K20 had that but i didn't think such a thing ever existed.... ive never seen it on a SPID tag and it isnt in my 1984 brochure.

I don’t really know. Snow plows are nearly nonexistent where I live. I don’t think there was a lot of different except maybe some trailer wiring between snow plow packages and camper specials.

 

[thatK30guy]

I've never seen any type of snow plow package ever offered directly from the factory except for dealerships as an add-on item only. There won't be anything on the SPID or RPO at all. Only thing shown are tow packages which consisted of hitches and tow hooks up front. Snow plows were purely dealer options.

 

[82355]

They didn’t.

Martin

 

[kennyw]

Take it for what it's worth but if you look up rear axle parts for a mid-80's Chevy K20 on any website it lists both the 9.5" and 10.5" rear axles as options.

Most of them also list the 10 bolt at the same time so it isn't a good point if reference.

 

[JoeliusZ28]

They didn’t.

Martin

The snow plow package or the full float?

 

[diesel4me]

Axle codes, or BOM (bill of materials), are sketchy at the most. While I'm not familiar with the specifics of the numbers/letters on BOM's it's the drivetrain shops that almost always ask or request of these digits when ordering the parts such as ring and pinions, etc., in order to get the correct parts. This leads me into thinking the BOM does identify WHAT the axle is but does NOT tell what ratio it has.

They probably changed the listings on "newer" trucks after '72--my old parts catalog shows axle codes like "RAW" ,a 3 letter code stamped on the RH axle tube,and it also lists what ratio it was,and if it was posi or not also...

 

[MTBLAZER89]

The snow plow package or the full float?

The snow plow package. It wasn't a thing. No RPO for snow plow package.

 

[thatK30guy]

The snow plow package. It wasn't a thing. No RPO for snow plow package.

Correct. Dealer add-on only.

 

[rksjd8420]

The snow plow package. It wasn't a thing. No RPO for snow plow package.

I may be saying it wrong from memory. The 10,000 pound gvwr single wheel 1 tons is what I was referring to. I think I remember the ones I have had as says something like snow plow prep package. The only difference was the overload springs in the back. They didn’t have any mounts or anything like that.

 

[diesel4me]

I recall the gas company my dad worked at had some early 80's 3/4 ton 2WD GMC's that were badged as "C-2500" but they were actually 1 ton single rear wheel chassis with the taller frame rails and had FF axles,they may have been "cab & chassis" special ordered,they put utility bodies and bucket lifts on them..perhaps they had the biggest FF available ?..

I have seen quite a few weird "fleet trucks" that other companies locally owned,and a lot of the time parts listed for what they were badged as didn't end up being correct,we had to match things up often..

 

[thatK30guy]

I recall the gas company my dad worked at had some early 80's 3/4 ton 2WD GMC's that were badged as "C-2500" but they were actually 1 ton single rear wheel chassis with the taller frame rails and had FF axles,they may have been "cab & chassis" special ordered,they put utility bodies and bucket lifts on them..perhaps they had the biggest FF available ?..

I have seen quite a few weird "fleet trucks" that other companies locally owned,and a lot of the time parts listed for what they were badged as didn't end up being correct,we had to match things up often..

Was the gas truck a crew cab? If so then that's normal for crew cabs to come in 2500's, or 3/4 tons, and still use the same frame and axles as a 1 ton uses. Just the springs made them different.

 

[6.2Blazer]

Most of them also list the 10 bolt at the same time so it isn't a good point if reference.

Again, take it for what it is worth but many sites only list rear axle options of 9.5" or 10.5". RockAuto and many R&P shops (like Randy's Ring and Pinion) only give you those options for rear axles. Several of the sites will list 8.5" 10-bolt parts but if you scroll down into the details it will specify front. However there are some that will state 10-bolt rear. Not trying to argue with you by any means as I agree with what you are saying. Parts store websites are definitely not the end-all answer to this stuff, but I have had decent luck cross-referencing parts in the past by seeing what numerous sites state.

Has anybody tried looking up factory parts at a dealer? I would think if both the 9.5" and 10.5" rear axles were available on something like an '86 K20, then at some point in time the system will start asking for what where axle at some point in time.

 

[bigblock454]

Kinda off topic a bit, but is the 14ff (10.5") still in production today for any use case by any manufacture?