I've developed another leak at the thermostat housing on my 1998 4.0 SOHC. I've found the post to upgrade to a better assembly, and I would be inclined to do so however the posts says to reuse the old upper half of the housing and that's where my problem is. I found a "non-oem" upper half at autozone to replace my cracked factory one. That worked for a couple months and another leak. I'm on my second one and same problem. I think the aftermarket one warps or something. I either need to located a "good" oem upper half to put on my existing lower, or do the uprgraded swap and still need an upper? Please help. The explorer has been out of commission since end of winter!! Need to get this bad boy fixed!!