I plan on replacing the UIM on my 99 Bonne. As I see it I have three options for the UIM: OEM, Dorman or APN. I would like to see comments, good or bad about any of these. The garage (not Dealer) that I plan to have do it will not warranty their work if the OEM is not used. (I told them I would supply the UIM because I did not want the OEM).

Either the APN or the DILLON. PM Bob Dillon here for that one.

Both of them are VAST improvements over OEM or Dorman.

The APN gives you a NEW upper with a factory-installed heat shield, reduced diameter stovepipe, a new UIM gasket and a throttle body gasket providing the best possible fix, and all for $115 delivered to your door. There is no better option.

Buy the APN and while it is all torn down, replace the LIM gaskets with aluminum frame GM gaskets, install new coolant elbows and flush the Dex, replacing it with "mixes with any color or type" long life coolant. Stick to your guns on the UIM. If your mechanic doesn't know about metal heat shields in UIMs, show him a copy of this Techinfo article: http://www.bonnevilleclub.com/forum/...e=article&k=38

Thanks Bill: I was leaning toward APN. I had read the article you referred me to earlier and noted this statment about the APN: "To obtain the larger .125” insulating gap in the newer 99+ models, the .750” shoulder of the replacement stovepipe provided in the kit could be machined to .625” to fit the smaller stovepipe bore in the lower intake manifold." Does that mean I have to machine that stovepipe to fit the LIM on my 1999. Thanks

Yes, you do.

If you get the newer kit, by the information that was given in this thread

http://www.bonnevilleclub.com/forum/...ic.php?t=74522

it would appear that APN is now shipping both sizes of the stovepipe with their uppers.

Oops. Forgot about that. This would assume there is no 'old stock' without both sizes still sitting on the shelf.

Not any more. Like Archon said, the newer kits now come with two stovepipes to fit all models from 95-05. (BTW, we are working on updating that information from Techinfo article 38.)

That'* not completely true. I purchased and installed the APN kit over the weekend on my '01 SE, and only received the larger stovepipe with my kit. I narrowed it to fit no problem, but it was a minor inconvenience. All in all it seemed like a nice kit, kind of a shame the UIM I replaced isn't even a year old (I guess the previous owner had it done not too long ago) and in perfect shape (GM part no less). I guess now I just need to hit up Dillon for a sleeve and I'll have a decent backup.

Tom

Tom, your APN kit was probably 'old stock' still in a warehouse or on the shelf when the new kits started shipping.