GMT900 w/ 4L60E - worth it?

I've been looking at GMT800/900 trucks recently - specifically the 1500 series ones. I know the 4L-60E is a trans on borrowed time, but that's what's available in my price range. The 6L-80E is much better, but that only came on the 1500s after '09. I don't want to go to a 2500 series with the 6.0 due to the gas mileage. I do like the GMT900 series because of the slightly better gas mileage (14/19 vs 13/17 of the GMT800). I do also plan to tow a ~5000lb trailer occasionally.

Would it be worth getting a GMT900 with a 4L-60, or should I just get the GMT800 with the 4L-60? Or would a high mileage (>150k) 09+ GMT900 be best decision?

I don't see the issue with getting an Early GMT900 truck with the 4L65-E.

SyntheticBlinkerFluid wrote: I don't see the issue with getting an Early GMT900 truck with the 4L65-E.

Is the 4L-65 the one in the GMT900's? I thought the 65 was for the AWD Denali versions.

I'm just worried about the self imploding 4L-60. The 6L-80 is touted as a great transmission since it's based off the great 4L-80

don't base your decision on an imaginary 1mpg that may or may not show up in the real world.. everyone i know with 88 and newer GM trucks and the common engines (350, 5.3) all claim about 15mpg, with slightly better mileage knocking on the 20mpg range when driven nicely on long trips.

regarding the 4L60e trans: they are good enough for most use as long as you take care of them, and the deep 1st gear compared to the 4L80e makes the truck a little more peppy in day to day use.

From what I've seen, I don't think I'd take specifically look for a GMT900 over a GMT800 unless the 900 had the 6L80. Between a later 800 and an early 900, I'd take whichever one was the better deal when I found it. No one I know with a GMT800 half ton has reported issues with their 4L60E. One of those trucks is a GMC long bed that sees both drag strip and trailer duty.

I have a gmt400 GMC Suburban that I am looking to sell if you are interested. Rebuilt trans and recently rebuilt 350. It has what I believe to be a wiring issue/pinched wire that causes it to run rough if the o2 sensors are hooked up.

I'm not telling you good or bad on them - I've just started reading about them - but don't forget the Hybrid exists.

09 and later, unique transmission that has two hybrid motors integrated, heavily optioned in the SUVs, reduced towing capacity (varies a little, but all are rated well over your 5000lb needs) and mostly similar used value to the pure gas models. GRM's new car review showed unimpressive mileage, but theirs died on them. Others report particularly good in town MPG when considered against the conventional. Lots of Hybrid specific parts - even the front seat backs are unique. Better 0-60 than the conventional.

Again, not saying good or bad, it just sounds like you're in a corner with transmissions and MPG, don't need to tow too much weight, and this might be an unconsidered option.

Borrowed time is an internet myth. Back in 1995 some dude towed in overdrive at 55 through hills with the trans constantly hunting 3-4, smoked it, posted on a newsgroup that all 4l60e are trash, and the internet has been running with it for 22 years

If a truck checks all the other boxes, dont be scared off by the 4l60. It seems like the trans is usually good for about 150k miles of moderate use. So one replacement or proper rebuild in the life of the truck. Its not like you will be pulling the trans with every tire rotation. I dont know what your situation is mechanically, if you can do the work yourself you save big money to the point that its nothing to fear. I just say all this because they really are great trucks.

Borrowed time is a real thing for 4l60e's, i didnt even get my info from the internet it came from work and seeing all the slipping and burnt transmissions in chevy trucks. Hell mines been rebuilt once (89k sunshell exploded) and im still scared too tow anything with it! My boss made 200k miles on his with some hard usage by flushing it every 50k and doing a filter every 100k. The undersized filter is why they burn up, the exploding sunshell was common in the early trucks, not sure if they ever improved on that design.

In reply to patgizz:

I have seen a few with the 3-4 having issues or reverse which runs through the same shell and there are upgraded parts available that appear to have identified the weak point. That being said I have a 2000 yukon that I bought from a friend with about 160k on it and the trans seems fine. Liek anything it can be hit or miss but is a weak point in an otherwise strong truck.

MINIzguy wrote: I've been looking at GMT800/900 trucks recently - specifically the 1500 series ones. I know the 4L-60E is a trans on borrowed time,

Only if you're a doofus.

Don't tow in Overdrive, if you do then only use OD when under light load and downshift BEFORE loading it back down again instead of letting the trans bang down by itself, don't smash it between Reverse and manual 1st (this rips the lugs from the case, used to see it every spring when people would tackle big gardening projects) change the fluid every now and then, and you'll be fine.

Shop truck has something like 260k on the 4L60, hasn't been out yet. Mechanical sympathy is your friend.

Also, change the diff fluid regularly too. With synthetic. GM made the 10-bolt a lot more reliable by specifying synthetic fluid so it isn't QUITE as bad as the previous gen where it'd eat bearings every 80-90k, but it's still the real weak point in the drivetrain.

In reply to MINIzguy: Any transmission can be ruined by failure to change fluid on a regular basis and driving "jerky" If the driver has a smooth foot that transmission will last well into the 350,000 mile range long after the dreaded tin worm has destroyed the rest of the truck..

I idly wonder if it's more simply that the DBW trucks can do torque-management tricks to make shifts feel smooth, which also greatly reduces clutch slippage, which enhances fluid/filter life. As well as makes life easier on the trans if you can have a set max torque per given gear.

Of course, the first thing the Internet says to do when you get a tuning package is to disable torque management. Then people wonder why they are suddenly breaking things.

Ah, this is all good news

Will be looking to test drive a GMT800 and GMT900 to see which I like more today. Could never find a good local Magnum RT, but these are easy to find.

My dad's 5.3 GMT800 has something like 210k on what he believes to be the original trans, the important details being the bigass auxiliary cooler, at least a couple pan drops, and not running it in overdrive when hauling or towing. The prior truck was a similar story on a 4.3 GMT400, it had glitter in the fluid at 280k when he sold it, but it still more or less worked behind the very tired 4.3.

Well, I test drove a '11 Silverado and an '04 Sierra ("cherry" 98k mile example) today. I preferred everything of the GMT900 over the 800, except the price. Didn't find a good condition early GMT900 to test out though.

I feel the real world gas mileage between the 4L-60 and 6L-80, between a 800 and 900, is a big difference. To accelerate at the same pace for the 800, it was revving out to 4k before shifting. The 900 lazily revved and shifted with the help of the 2 extra gears. I wonder what the shift pattern is like for the early 900's.

Get whatever floats your boat. Dad's had 190k on the original trans with 2 fluid changes. I'm at 90k on my 06 with changes every 30k. The trans is not the weak point like the dodges of that era for certain. 2WD 800 got the R&P steering and drive great. will get you low 20's when driven properly. Dad's '03 3.42 5.3 gets 20-21, my '06 3.23 4.8 gets 22-24 on the highway and apparerntly 19 with my daily slog to work of 12 miles of 60/40 back roads and city stop and go. They're great trucks, drive well, hold up and run forever. IIRC, mt former boss had an 03 'burb 5.3/4L60 with 300k before the first trans. He had CSK (Cold start knock) since 110k and last I heard has now eclipsed te 400k mark on the same engine. still rattles at start up, goes away warm.

Bobzilla wrote: Get whatever floats your boat. Dad's had 190k on the original trans with 2 fluid changes. I'm at 90k on my 06 with changes every 30k. The trans is not the weak point like the dodges of that era for certain. 2WD 800 got the R&P steering and drive great. will get you low 20's when driven properly. Dad's '03 3.42 5.3 gets 20-21, my '06 3.23 4.8 gets 22-24 on the highway and apparerntly 19 with my daily slog to work of 12 miles of 60/40 back roads and city stop and go. They're great trucks, drive well, hold up and run forever. IIRC, mt former boss had an 03 'burb 5.3/4L60 with 300k before the first trans. He had CSK (Cold start knock) since 110k and last I heard has now eclipsed te 400k mark on the same engine. still rattles at start up, goes away warm.

Are those 2WD numbers or 4WD? And are those highway speeds doing 65 or 75?

I just know back when I drove the 900's with the 6 speed, 5 people and packed to the brim with luggage, I was able to touch 20MPG doing 75. I didn't think an 800 could get those numbers, but I only did a short drive with one.

I'll still have to look for more 800 trucks, especially a 2WD version. I want the newer ones, but the budget doesn't allow for it.

Both of ours are 2wd. Back pre-ethanol days our 24mpg was 2 adults, 2 dogs and a bed full of crap at 75mph.