Joined: 30 Apr 1999
Location: 2000 Silverado Z71 4.9L 4L80E, 2003 Lincoln LS 3.9L V8 5 speed auto
If it's flaring it's dying. Pull two quarts out, replace with one quart TransX and one quart Lucas trans additive, then take it easy on it. Every 4LPOS60E I've had that has problems has gotten this treatment and has lasted until I had the cash to get a trans together.
3600 bucks roughly, and I don't remember if that included the TCI low gear unit that changes from a 1st 2.48 2nd 1.47 gear ratio to a 2.75 1st 1.57 2nd gear ratio. Well worth the money to add this in, although Chuck won't be too happy if you want one after all the problems he had with mine due to TCI not machining the unit correctly. He worked with TCI on it, they back and forthed it a few times, and he was able to get them to correct it but he said it was a huge headache. But I gotta tell ya, the 2.75 gives me almost the same acceleration as the 3.01 and the 1-2-3 shifts feel right. It doesn't feel like there's too much of a drop like the 3.01/1.47 does. When I test drove a stock 4L80E, the 2.48 1st made the 6.0 in the truck I was driving feel more like I was taking off in 2nd in my own truck. You wouldn't think that little bit of a difference would be that noticeable but it is. They also make a 2.97 1st, but that one is about 600 bucks more than the already high 2.75 is.
On the U-joints, so long as you don't use the ones with the grease zerk in the body of the joint itself. Those always crack on me within a year with the crack starting at the zerk hole. That hole in the corner is a huge weak spot.