Here are my recommendations for UIM/LIM repairs for the 95-05 L36.
Please note that if you cannot wait for parts in the mail, you will not get the best fix.
The best fix for the LIM - GM aluminum frame gaskets......$59
The best fix for the coolant elbow(*) Dorman Help.........$6
The best fix for the UIM - APN upper intake manifold kit......$115 including shipping
In addition, I recommend the following steps to keep engine operating temperatures down, to ensure that coolant flows around the hot stovepipe area in the plastic UIM, and to eliminate any possible harm from the use of Dex-cool - all factors that protect and extend the life of the UIM and LIM gaskets.
Flush coolant and re-fill with "mixes with any color"
Drill a 1/16" hole in a 180F thermostat flange and refill according to: http://www.bonnevilleclub.com/forum/...=article&k=100
Install an after-market transmission cooler.
I use only a scraper and degreaser to clean gasket surfaces on the cylinder heads to avoid introducing abrasives into the engine.
Regarding the UIM, the longest-lasting fix will come from an upper intake manifold protected by a heat shield and the use of a reduced diameter stovepipe to provide an insulating gap between the hot stovepipe and the metal heat shield. The only commercially available kit that provides those features is from APN. Dorman UIMs have NO heat shield protection for the plastic EGR bore, but rely solely on the insulating gap provided by a reduced diameter stovepipe.
UIMs can be sleeved, plugged, and otherwise repaired for re-use, and these repairs can be made at low cost. But, unless the UIM is fairly new, most will typically exhibit warpage at the throttle body sealing surface and at the coolant passage sealing surfaces around the EGR bore. When considering repair of a UIM, don't forget to add the costs of a new UIM-LIM gasket and throttle body gasket, typically about $45.
From Sears, a smaller 3/8" drive deflecting beam type torque wrench does just fine for UIM/LIM work. It costs $25. http://www.sears.com/sr/javasr/produ...id=00944690000