I have a 4L80E in my 91 blazer never had any problem with the Trans
What I did when I first got it was first put in the biggest trans cooler you could get second thing I did was install a spin on oil filter kit on the return trans cooler line like the Allison trans has
And the third thing is I run all synthetic oil and fluids in it when I was working I
Towed& pulled in and out of 4x4 and really used her and as of today the tranny still works great at 150.000 miles
Every 5000 miles when I change the oil I just spin on a new filter for the trans fluid is still red This might sound like over kill but it works
