4l65E stock or added later?

[LargeSarge]

I have a 2005 GMC Yukon SLT 4wd. I am replacing the engine with a low mileage engine (5.3 LM7). I just bought the truck and the seller was dishonest and hid a ton of problems. This is my first LS platform and I am learning as I fix the many issues with this truck. I had done some research on the 4l60e and assumed that is what this truck had. It also has the RPO code M30. To my surprise, after getting the engine out, I noticed the center bolt hole associated with the 4l65E. Is there anyway this could have come stock? Or, did it have to be dropped in later in the life of the truck? The truck has 188k miles on it. I assume the trans will go sooner than later. I am hoping this was replaced in the last few years.

 

[swathdiver]

If it's a reman from GM, there ought to be a stick on top of the case. What do you think Nick? @NickTransmissions

 

[NickTransmissions]

@LargeSarge , that trans appears to be the original unit; converter hasnt been changed as its still the same TMBX converter that GM installed (unless someone swapped in another, identical converter into it at some point).

M30 is the regular production option (RPO) code for the 4L60E (M32=4L65E; M70=4L70E)

The center bolt on the bell is there on all 4L60Es that went in behind Gen3 small blocks. The 4L65s went into high end truck/suv submodels as well as Vettes & GTOs of that era.

Id rebuild that transmission while its out: 188k youre in the last 5% or so of its life expectency.

 

[SnowDrifter]

188k youre in the last 5% or so of its life expectency.

Stop talking

I'm at 175k. Original 4l60e. This is fine.

 

[NickTransmissions]

Keep up with service and dont overheat it and you may be able to get many more miles out of it before it goes...