GMT800 vs GMT900, 6.0/6.2 vs 5.3

I'm long overdue for a new tow rig. Sold my 2006 Seirra 2500 (2WD WT Trim) before moving south since it featured a bit more Ohio than I liked. Assumed I'd replace it with an equal, Ohio free truck when I settled in, only for prices to keep increasing... Still regret selling that truck, really don't want to do brake lines again.

The new (to me) truck's only responsibilities will be towing the MRS to/from the track & assorted house duties. Generally speaking, I'd like something similar to what I had, old and reliable. It was definitely overkill, but it was more than enough if I ever wanted to upgrade to an enclosed trailer. That said, most of what I've seen for cheap (govdeals....) lately has been later GMT900 trucks with the 5.3...

That all said, how much difference is there from GMT800 to GMT900? Anything I should watch out for?
I'm assuming anything GMT900 with a 6.0/6.2 will be more than adequate. However for the 5.3 I'm seeing a wide range of towing capacities listed. What should I be looking for if I go with the 5.3?
Finally... Transmissions... Do I need to avoid any?

Definitely the gmt900 with the 6 speed automatic. The extra 2 gears makes a big difference when towing in my experience with both of those. 
As far as which engine, I think either the 5.3 or 6 should be ok depending on how much weight you're towing. Bigger is always better of course. 
 

I thought the 5.3 was only in the 1500 and the 6.0 in the 2500?

In reply to TheBerrynator :

The 6 speed performs better but the torque converter likes to die and take out the rest of the trans with it. 

The 6.2 will be non DOD

If reliability is what you care about I'd be looking for a GMT800 1500hd or 2500 with a 6.0 4l80e combo. Plenty of headroom for future pulling and reliable as gravity.

DOD might be a thing on the 5.3.  I've heard it can wreak havoc.  When working properly it seems seamless though.  Not sure what it really does for mpg.

In reply to A 401 CJ :

DOD will be a thing on the gen 4 5.3s. It's not as bad as on the GenV LT based stuff. Lots of the LT based stuff is happening very early, like before the first oil change. They are also magically bending pushrods and the occasional dropped valve.

The Gen4 stuff normally comes with mileage, and some people don't suffer it. My parents have a 12 yukon at 200k miles and no noise. Mom changes the oil every 3k with synthetic though. The local GM dealer are saying they are seeing it in the low to mid 100k mile range for people running GMs recommended OCI. So it appears good oil changed regularly can stave it off for a while. I'd probably do a good synthetic at 5k miles. Cam damage is also much rarer on Gen rs vs Gen 5s. I think most GRMers are capable of doing lifters or even changing a cam on an LS. I've had an LS head off in under 2 hours.

What I'm saying is because of the 5th gens crazy DOD failure the hysteria is also affecting people opinion of the Gen 4s but they aren't near as bad.

DOD is definitely something to consider when looking at a GMT900 especially used with some mileage but by itself it wouldn't stop me from buying one. The combination of DOD and a failure prone trans (6speed) would stop me from buying one if I wanted to use it for truck stuff.

For me truck stuff needs to be handled by something super reliable that I never have to worry about. I just have to know it will start and run fine everytime. So to me the availability of the GMT800 1500hd which is more capable and has a more reliable engine and trans, rules out a gmt900 with the 5.3

Towed the same trailer back to back with a 1/2 ton gmt800 and 1/2 ton gmt900. The 900 towed much better. You will like the extra gears. NVH seemed much improved as well. Fuel economy was ~15 on I95 and I think it was using the DOD even under load.

If you don't need a pickup, it seems like Cadillac Escalades tend to be a relative bargain, and several years of them do not have DOD.

codrus (Forum Supporter) said:

I thought the 5.3 was only in the 1500 and the 6.0 in the 2500?

1500HD came with a 6.0l and 4L80E (and 4:10 gears).  I have one, it's for sale, but its got lots of Pennsylvania. 

Alright awesome, Thanks all! I was trying to find this last night, but I feel like my ability to google anything tanked once I hit 30... As far as I can tell, the GMT900 5.3 should come with the 6 speed as long as it's not a single cab, is this correct?

Start reading Summit Racing's documents on which motors don't have DOD (AFM) and what years they were on. https://help.summitracing.com/app/answers/detail/a_id/4851/~/intro-to-the-l92%2C-l9h%2C-and-l94

I was looking last summer and decided I wanted an 07-09 Yukon Denali XL or Escalade ESV for the 6.2, 6L80 and no DOD. E85 compatibility was offered for the 09's too.  Prices were also too high for me to justify a nearly 15 year old GM product, so I went another direction.