Is this possible to use the metal upper plenum from a Series 3 mill in place of the plastic Series 2 plenum? The lower intake manifolds are the same part# (24508923)...

Someone told me this was possible...I haven't found an online source to confirm...

I don't see why not. If it is physically the same (TB hole size, etc) it just may work.

You need a throttle body adapter. The TB'* are not the same.

I believe INTENSE sells them.

only i believe they sell the Gen V adapter plate and not the L26 adapter plate...

MANY of the GP guys have done this already, and if your also gonna do this i recommend doing the Lower intake gaskets at the same time

The TBI'* aren't the same...I compared the 2006 Lucerne listing versus my 2004 Bonneville...I think most, if not all the series 3 are drive by wire...

My Bonneville is still under warranty...had to have the lower intake resealed as the RTV @ the end seals were leaking...got the new GM metal intake gaskets in it now...
I just don't like the plastic plenum...



Thanks for all the responses, BTW!!!

Talk to Bob Dillon and Bill Buttermore here.

We can set you up with a modified Plastic UIM with blocked coolant passages and a reduced diameter EGR stovepipe for about 65 bucks. The only other cost will be your gaskets and shipping to send your core manifold back to Bob Dillon for modification for the next person.

I just installed one for a member this past weekend.

Ok I'm missing something here.

You would want to have the coolant passages blocked off because ... ?

That is an option, not a requirement. It'* the improvement in the EGR area that is the key to the design.

I ordered the series 3 plenum...I'm gonna to try & match it up with the original plenum & see...

If not, I won't worry for now, as my Bonneville is still under warranty, and I can return the plenum if I desire without issue...


Thanks for all the answers though!!!


I'd like to know more about the whole modification process! You all should advertise it somewhere!!!

Advertising isn't necessary. Virtually every member here is familiar with the Dillon/Buttermore work, and we now have 25 intakes installed on this Forum.