4L60E Transmission lost the front pump at 100K miles.
I replaced this with an after market pump. The original was poorly built.
At 120K miles the plastic radiator drain plug disintegrated while driving. I replaced this with a stock part from a local parts supplier.
At 125K miles the water pump began to leak so I replaced it.
At 127K miles the oil cooler hose ruptured. Upon examining the cooler assembly I discovered that the rubber lines are crimped to the metal lines attached to the engine. This design is just a complete insult, there was no reason to make it all one piece. I had to lift the engine one inch in order to remove the lines so I continued removing until the complete oil cooler assembly was gone. I purchased an oil filter tube for a 1996 Chevy Safari Van, which also uses the 4.3L engine. I installed the oil filter tube in my Blazer engine, now the oil filter is on the engine block where it belongs.
At 140K miles the fuel pump died. When I removed it I discovered that the wires inside the tank as well as the plug was melted. Several times just before the pump went out, while fueling the vehicle, I noticed a mist, almost a steam, coming out of the tank as I pumped the cold fuel in. I suspect the electrical current in the fuel caused it to heat. I have no explanation why it did not explode. In searching the web I have numerous posts that reflect this same problem, GM must know that they have true bombs on the highway.
Presently at 145K miles the transmission has lost the reverse gears which is another known problem with the 4L60E.I am replacing the complete transmission with a used one and when this the Blazer rolls again it is gone to a new home.