K-2500 six hole

[1976gmc20]

I've been looking for another pickup and came across a nice 1988 K-2500 light duty with six lug wheels.

So what are the advantages of this over a K-1500 ???

I'm assuming you get a stouter semi-floating rear axle, heavier rear springs, and probably stouter ball joints, etc and maybe a stouter front differential. Is any of that correct?

What do I lose NOT getting a 2500 HD eight lug? The idea is to put a tall camper shell or pop-up on it.

Which automatic transmission would this have in it? (I would prefer a manual but my wife needs to be able to drive it)

[cashforclunkers]

14 bolt sf rear instead of 12. Nice axle.

Probably in 88 would have a 700R4

It's a cool truck i'd own it. I had a 98' 2500 and it was my favorite truck to date.

[95 S_Trucker]

Front suspension and front differential is the same as 1500 trucks

The transmission would be a 700r4 or a th400.

1500 trucks- 6000 gvw

2500 light duty 7200 gvw

2500 standard duty 8600 gvw.

[95 S_Trucker]

Originally Posted by cashforclunkers

Probably in 88 would have a 700R4 (the light duty option) or 4L80 (non -E)?

There never was a 4l80e that wasn't electronic. The 4l80e replaced the th400 in 1991. The only 4 speed auto before 91 was the 700r4.

[cashforclunkers]

Originally Posted by 95 S_Trucker

There never was a 4l80e that wasn't electronic. The 4l80e replaced the th400 in 1991. The only 4 speed auto before 91 was the 700r4.

Sorry I thought there was. I guess I would have run into one by now if that were the case. I'll edit my post so I don't misinform.

This must be why I was confused: (from wikipedia)

For 1987, GM changed the nomenclature of their Turbo Hydramatic transmissions — the THM400 was renamed to the '3L80' (three forward speeds, longitudinal positioning, and an arbitrary 'strength' of 80, the second highest such rating assigned). The 3L80HD was introduced in 1987 as the HD unit used in passenger trucks. In 1991, a four-speed overdrive version, the 4L80-E, replaced the THM400 in Chevrolet/GMC pickups, vans, SUVs, and commercial vehicles.

[1976gmc20]

Thanks, everyone! I learned a lot.

So this red/silver pickup could have a TH400/3L80, which means it would be a 12 mpg pickup. Or else it could have a 700R4. The latter is what I have in my 1991 Suburban which has yet to be a problem even though we've towed a trailer with it some, and I expect that's mostly what it did before we got it. It might have been rebuilt by a previous owner.

And it seems the only difference between the 1500 and 2500 6-hole is the rear axle and springs? That makes it more like a "heavy-half" than a 3/4 ton.

[special-K]

Originally Posted by cashforclunkers

14 bolt sf rear instead of 12. Nice axle.

Probably in 88 would have a 700R4

It's a cool truck i'd own it. I had a 98' 2500 and it was my favorite truck to date.

I'm not teaming up on you. Just using your post for a start.

It's more like 14-bolt semi-floater rather than 8-lug full-floater in K2500 comparison and 14-bolt SF vs 12-bolt in K1500 comparison. Don't know if there were 8-lug K2500s with 14-bolt SFs in these years, except Suburbans. My experience in these pickups is limited to diesels which got FFs.

GM was playing games for average emission requirements across the full line. They offered 6-lug K2500 Suburban 6.5TDs for the same reason, With the '88 pickups it may be more of offering a middle range, not sure. I know I was very disappointed in GM in '88 when these trucks came out (mid-'87) after the long run of square bodies and I was only seeing 6-lug K2500s. I don't recall seeing the 8-lugger K2500s at all at first.

The first 4l60s were renamed 700r4s in '90. In '93 the 4l60E came out. This is the first time I ever saw the TH400 was called a 3L80. I hate name changing. About as worthless and foolish as things get. If you want to actually change something, change it for the better or leave it alone. But names??? Uh, their whole purpose is for the sake of identification. right or wrong, the name anything or anyone starts off with is their identification. You change that and you lose identity, at least until the word gets around... if it does. Very simple cut & dry matter here. Historically, changing identity is a shady deal.

Chubby: "My Chevy has a 3L80"

Jimmy: "It has a what? I've been a GMC fan since the '60s and I never heard of such a thing"

Chubby: "It's a TH400 but they changed the name"

Jimmy: "A TH400? Why didn't you say so?"

[1976gmc20]

Like I always carry a LHRPS in my pickup in case I get stuck

(Long Handle Round Point Shovel)


I probably won't get this one because I don't really have the money in hand right now. But it's good to know that there are at least a few nice old regular cab long beds available. I'm hoping to find a real K2500 that still just has a 350 and not a 454.

The plan is to head down that way tomorrow (we were supposed to go this morning but had 1.5" of rain and couldn't get out with the car). No time to stop in Fort Collins on the way down, but if it's still available by the weekend I might see if we could stop by on the way home and take a peek at it on Sunday morning.

The only halfway reasonable time to try to get through Denver is either mid-day mid-week, or early Sunday morning. So all of our trips to Coloradofornia have to be scheduled around those time slots.

[abig84]

I would think it would do a camper shell no problem. My old job had a 91 c2500 we used as a scrap hauling truck. 2000lbs in the back of that thing was no problem, rear sat a little bit higher so that much weight just leveled it out. If i put that much in my 1500 its almost on the bump stops

[special-K]

I was looking for a regular cab (I guess we have to say that these days. Really it's just a "cab") K2500 or SRW K3500 when I ended up buying the K2500 Suburban I run now. Harder to find a clean truck that a Suburban and what I was finder was a pickup with same miles, condition, don't care about year, were running on the average $1,500+/- more. I guess and older SUV carries no status (like when older Cadillacs were cheap) and an older truck is still great as ever for hauling. Always a value there as a firewood/junk hauler if nothing else. So now my truck is a Suburban 350/4l80e/4.10/hydroboost hauling machine. MPG sucks, though. About 10. Funny how my '72 K2500 with 350/TH350/4.10s gets the same. Where did all the F/I and O/D get us 23 years of technology later?

[1976gmc20]

Our 71 K-10 got about 8-10 mpg with the TH350 (~55mph)

91 Suburban gets/got about 15-16 mpg at 65 mph with the 700R4.

Not sure what my 5 speed 89 K1500 gets since I drive it off road so much. I thought it was about 15 mpg the first couple tanks with on/off road mix of driving.

My experience is that manuals always get a lot better mileage overall. My 77 and 76 2wds with four speeds and no overdrive got 15-18 mpg.

I hear what you say about used Suburbans but we already have a 4wd squarebody TBI that just needs some fixing up. Converting it to a camper just doesn't seem to be an option. As much as I like the solid axle 4x4's, I have to admit that the 1988++ pickups are better for a lot of highway driving.

So basically I want to find a nice 1988-95 K2500 to replace the Suburban, and eventually find a usable 73-87 K-20 4 speed to replace the K1500 "ranch" pickup.

[special-K]

Carburetors can vary by 50% or better. At one time I had two '72 3/4t 4wds and both got 12.5 mpg. I had no speedometer or fuel gauge in my GMC for a while and would go by full used in the Chevy to a job to gauge fuel used in the GMC for same trip. Consumption was the same. Here is how they were equipped:

'72 K2500 - 350/TH350/4.10 33/12.50 all terrain tires

'72 K/20 - 400SBC/4spd/4.10 35/12.50 all terrain tires

That direct lock up 400 took very little throttle to roll it along... effortless. The engine, tire diameter & trans differences seemed to balance out. But now the GMC gets 10+/-. It has higher compression heads now. If it was a 4spd that may have helped the consumption, I figure.