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Did any 3/4 tons get 14 bolt full floaters after 1981?
- Thread starter 82355
- Start date
dirtygoat
1/2 ton status
Not sure how I could prove it...
Bumping this one back up in case anyone has found any more concrete info. Curious because I've always wanted to solve the mystery about what my grandfather's truck was. I was talking to the guy he sold it to this saturday and he was telling me about how he was surprised that it had a Detroit Locker in it, which he found on inspection due to how unfriendly it drove in comparison to all his other trucks. He and my father both claim it was 85 3/4 ton but not sure how much I trust their knowledge. They may be confusing a semi-float gov lock or it might have been a K30 for all i know. What I know for sure is that it had factory dual batteries and a 350/400 driveline. As a kid I can remember it having BFG all terrains and cab lights when it was basically brand new. My grandfather may have added those items though, i know he added cab lights to another one of his trucks. It also sat with a slight forward rake which I've noticed is indicative of C6P chassis/springs on other K20s. Unfortunately the truck is long gone so I'll never know for sure.
81-91 square body 3/4 tons only got a 10.5” 14 bolt if they had a 454 or were in a crew cab. Only way to get a 454 in a 3/4 ton was to get a 2wd. So no 4x4 3/4 square body had a 10.5” 14 bolt after 1980.
You could get a 14ff in a non bog block truck, all how it was ordered. 2wd or 4wd...
Any insight to GM’s rationale for the change to the 14sf in 3/4tons and burbs? Maybe rotating mass/fuel economy? Just trying to see their logic (even if it was flawed). Maybe to just have more differences between 3/4tons and 1 tons (aside from the d60 and big block)? But why leave them in 2wd (i get the combo w/ big block) but why not offer big block in k20’s and burbs?
Sure could. Crew Cab or 1 ton. Not in a regular cab 3/4 ton.
Wrong. I've been junkyarding for 25 years. Big blocks are next to impossible to find in a junkyard. I've seen many 3/4 ton 2wd's with small block or diesel with 14ff. It's how the truck was ordered. So if someone ordered a heavy duty camper special, it would come with a 14sf? I'm sure they are scarce, specially now that cash for clunkers and hi scrap prices. And in my area, RUST....
Not on 81 up square body. The only exception might be a cab and chassis but I don’t think they had a cab and chassis that wasn’t a 1 ton.
What camper specials or any non crew cab 3/4 has a higher gvwr than 8600 pound gvwv other than a 1 ton are you seeing? Before 81 there were but I have never seen a regular cab or suburban 81 up square body that has a gvwr over 8600. 1 tons were 9200 or 10,000. 3/4 tons were 8600.
What camper specials or any non crew cab 3/4 has a higher gvwr than 8600 pound gvwv other than a 1 ton are you seeing? Before 81 there were but I have never seen a regular cab or suburban 81 up square body that has a gvwr over 8600. 1 tons were 9200 or 10,000. 3/4 tons were 8600.
See I've always understood this to be the "rule" but now that I've dug into it a bit I'm seeing more examples to the contrary. The people that say "well my 84 K20 has a 14FF but its a mud truck that's had 12 owners and 3 different lift kits" are not what I'm talking about. I haven't found any GM doc on it, nor have i found what would have been the option code if it DID exist. Here's an example from another thread on this site about C6P trucks:
"We had 5 K20s from 81-87 and they were all C6P, but we ordered them that way. 3 of them even had the 14Bff which surprised me after i knew the difference. and one had bucket seats too."
Right now I still think that all 81+ 4x4s got semi-floats, but I'm not confident enough to call other people a liar yet.
I don't think its that easy because I have seen plenty of C6P's with semi floaters. If it did exist I think it would have been a separate option that required C6P.
This won't clear it up. I can't search the catalog by option. Just year, make and model. By looking it up as an '85 k20 truck these are the options found when diving into the rear axle:
It shows all 3 axles from the 8.5" 10 bolt, 9.5" semi floater and the 10.5" full floater. It won't show me how the trucks were configured when ordering, but this is what was available.
I would not quote it chapter and verse as the be all end all authority either. I've found info prior to the mid 90's gets sketchy in the electronic catalog. But even the paper parts catalogs didn't dictate how it was built but what was available.
What's needed is a glimpse at the truck order guide that dealers would have used to aid in option availability and compatibility. Not many survived as they got tossed year after year as new models came out.
Think you need an RPO decoder to get into more and deeper specifics. The SPID and RPO give each trucks vitals and details to a certain point as they're not always 100% spot on.
It's going to come down to that because looking at the 1985 truck info from the GM heritage site it does not break down the physical type of axle on any model of truck to the ring gear size. Only weight capacity. What they do show is the k20 without c6p has a 5,700 pound rear axle weight capacity vs K20 with c6p had a 6,000 pound axle weight capacity.
Is 300 pounds difference in capacity the signal to go from a 9.5" semi floater to a 10.5" full floater? I don't know.
I believe the 300 pounds difference is only based on the change of leaf springs. The full float axle would not have been included by default with C6P since there were definitely C6P trucks that came with semi floats.
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)..
My old GM parts manuals used to list them that way..(!946-72 catalog I have)..
This ^^^^^^
