carkhz316

Wow. Haven't seen BCM issues like that very often.

Its a common problem that the TCC pistons crack in the 4l80 transmissions, at least on the later ones. If your mechanic has confirmed as such, you could be alright with just the TC replacement. However, the valve bodies have issues with high mileage wear as well, as mentioned above. It's kind of up to you how much money you want to spend for piece of mind vs. how long you plan on keeping/ driving the truck.

^What he said. As a quick and easy check, unplug the main transmission electrical connector and drive it down the road. It should default to 3rd gear (limp mode) if the clutches are intact, but if they're not it'll take off in 1st as before.

2 in 5 years does seem strange. I would chalk it up to being a fluke, as theres not much in the brake booster to go bad besides leak.

Gee whiz.....with the public's obsession over having latest and greatest, most notably perpetuated by cell phones and the like, it's no wonder vehicles are so fickle. Barely get the bugs worked out and everyone is chomping at having another, because yesterday is old news.

Good info. You should post more in transmission threads. I was about to say that it would bolt up, but realized you're correct about the HD 6.0s having the longer crank.

This! Apparently most people haven't heard of an iron remover. This will take care of most if not all the brake dust. You may have to clay and polish a bit afterwards, but I'll be surprised if any painting or replacement has to be done. Worst case, talk to a detail shop before you get too crazy OP!

Can you open a graph display of the upstream O2 sensors and log that while driving? Or at least indicate what the display is showing when your truck acts up? I would be inclined to think, based on some rich long term fuel trims, that you're suffering from a ignition miss, presumably under load (most common) which would explain the chugging at highway speed. Alternatively, if it were indeed secondary ignition problems (plugs and wires), you could put your foot on the brake and rev it to TC stall (don't do a burnout), to see if the engine starts missing.

Do you mean the brake booster or the power steering pump?

Well, you're probably right but then they must get a little fuzzy on the details because all of the literature I've found don't elaborate on much. I would assume that the chain and sprockets are likely the only difference between the LD/HD variants. The rebuild kits and parts I've purchased don't differentiate between the HD/ non HD. Also, the last one I fixed out of a '02 2500HD 6.0 simply had "NP263" stamped on the circular tag. I know these aren't the greatest sources (wikipedia doesn't have much beyond the model breakdown), but neither of these differentiate between the HD/ non HD https://spprecision.com/products/np261-transfer-case-sale.html https://www.ebay.com/itm/Transfer-Case-Rebuild-Kit-NP263-NP261-LD-HD-GM-CHEVY-GMC/181947396245?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649

To clarify a little bit further: davester you're pretty much correct. The only thing is that the NP261/63 and HD are one (two?) in the same. It's the "XHD" variants that are the ones with a slightly larger input and output shaft. Those are found behind the 8.1/ Duramax equipped trucks. What I assume happened is this: the mechanic saw "2500" and assumed 2500HD for the transfer case rebuild (which he'd need a 261/263 kit). However, OP's truck uses the same as the 1500 transfer case, which is a NP246 (rpo option NP8 I believe).

Yes and no. It will physically bolt up (save for the 97 won't have the bolt hole in the 12 oclock position), but it likely will behave erratically and may not shift due to electronics and pump differences between those years.

Those are chassis codes and won't keep your engine from starting. When you say it tries to start, what do you mean exactly? Does it crank but not fire, or does it sputter as if it's about to start? Have you checked fuel pressure, spark, etc?

99-02 trucks had ignition switch issues too. Is your truck driving irregularly when you notice it acting up?

Ah gotcha. Ya, sounds it like OP might be have some trouble anyway, as I ignored the fact that his has a input speed sensor (2007+ had this), which pretty much requires Trans R&R to get the boost valve out.