Please allow me to share my experience dealing with General Motors and their warranty coverage. I purchased a new General Motors Performance Parts 4L85E Supermatic transmission and installed it in March of 2015. My car is a 1970 Camaro and it has a GMPP LS376-480 engine which was also purchased new. The car does get driven but it has never been raced or abused, and in general it spends a lot of time in the garage (average use is approximately 2000 miles per year). I completed these installations myself, but I have been working on cars for almost 50 years so I am confident that everything was properly installed. In September of 2017, after approximately 5000 miles of use, the transmission began to malfunction. Under certain conditions it was slipping instead of shifting. I didn't know what was wrong (I thought it could be something minor) so I took it to my local transmission repair shop. The technician started by pulling the pan. He noted lots of metal fragments, so there was no alternative but to remove the transmission for further evaluation. He told me that the overdrive sprag had failed, which he said he hasn't seen very often, but his best guess was it was just a defective part to begin with. He also told me that this failure resulted in metal fragments which resulted in damage to other components in the transmission. The only solution was a total rebuild, including replacement of many hard parts. This cost me $2364.50. I realize that quality control of parts is not a perfect science, i.e. once in a while a defective part is going to make its way into an assembly, even at General Motors. I thought that General Motors had a good reputation for standing behind its products so I sent in a warranty claim form (using the address on the form) along with a detailed letter, receipts, and appropriate documentation. I ended up sending in three such inquiries over the course of approximately three months. All mailings were via certified mail, so I know that someone at GM received my inquiries, but I received absolutely no reply or acknowledgement! I could not find a number to GM customer service, so I called Jeg's instead (since I had purchased the transmission from them) and they provided a phone number. It wasn't quite the right number but it was a starting point for what turned out to be over three hours of telephonic frustration. To label it a "runaround" would be an understatement. I spoke to 6 people at 4 different phone numbers. I was put on hold many times, and was asked at least four times for my VIN, which of course is absolutely irrelevant in this situation and which pointed to the ignorance of the person I was speaking to. I was given "excuses" for non-coverage, such as there had to be a service bulletin or recall...or they won't cover any parts installed by the owner, etc. At one point I asked to speak to a supervisor and was promised a return call which never came, so I had to start over with yet another person. Ultimately all of these representatives said "no", and then when I would not accept that, said that they weren't really the person I needed to talk to, and then they would give me a different number to call. (Why couldn't they have said that at the beginning?) After spending most of the afternoon on the phone and after having to resort to what I would call a heroic level of assertiveness (which is very out of character for me), I got to speak with supervisor Meredith at 800-450-4150. She seemed very nice and seemed to want to help, so I thought that perhaps I was finally speaking with the correct person. She at least seemed interested in knowing the facts of my case. She said that my transmission would have warranty coverage for 3 years or 100,000 miles. However, they would only provide coverage if the repairs had been provided or approved by an authorized GM service center. She said that is their policy and it is in the written warranty information. At least she gave me a reason, though not a valid one, in my opinion. Supervisor Meredith proclaimed herself to be the ultimate decision-maker for GM, so apparently I have no further recourse. I feel as if I did as any normal person would do... When my transmission started slipping instead of shifting, I took it to a transmission repair shop to have it evaluated. I did not know at that time that I was looking at total rebuild. I submit that it is totally unrealistic to expect that anyone in this situation would stop before doing that to read the fine print in the GM warranty about getting a "blessing" from an authorized GM service center before proceeding with repairs. In my opinion, things like that serve only one purpose--which is to give GM an excuse to not pay. If they wanted to help a loyal customer they could make an exception--but they apparently don't actually want to help, so they hide behind their self-serving policies. I had purchased this transmission new for $2849. I could have gone with something less expensive, but I chose to purchase a new-from-GM, heavy duty transmission, expecting that it would be reliable and would have a long service life. So I am very disappointed in how it failed catastrophically after only about 5000 miles of use. The other reason I purchased a General Motors product was because of my expectation that in the unlikely event of a defective part, they would stand behind their products...but it turns out that they do not. I used to consider General Motors to be a reputable and ethical company, but sadly that is no longer the case.