I recently purchased a new grip housing for my CA89K to replace the plastic lower that looked like a monkey made it.  I purchased a steel SP89 metal housing can I take the internals from my polymer one (except the selector switch) and just slide them into the metal one with a new selector switch and install or do I need new housing that holds the trigger and hammer ejector.

The trigger pack should be able to be swapped out from one grip to the other.

You need a SEF style trigger group for a metal lower... if you had the picto navy ambi lower then it won't work

Quoted: You need a SEF style trigger group for a metal lower... if you had the picto navy ambi lower then it won't work

Can you please elaborate on the difference?  Or where I can get the one that I need?

Anyone, I want to try and finish this project soon?

If your CA89k came with a grip housing that had selector levers on both sides (ambidextrous), then the pack won't work in the new housing.  If your old lower had only a lever on the left side, then you only need a new lever for the thinner metal housing.  I'm almost sure that your CA89k had the lever on both sides and the holes in the trigger box that the ambidextrous levers fit into are bigger than the hole of the single lever box.  What you needed was a clipped and pinned ambidextrous pack housing to swap out on your gun.  Make sense?  Hope this helps-ARKAR

Plastic 'ambi' housing -


pic courtesy of HKParts.net

Ambi trigger pack -


pics courtesy of HKParts.net

Ambi safety selector right side - left side.



pic courtesy of HKParts.net

Steel 'SEF' housing -


pic courtesy of AA-OK


SEF trigger pack -


pic courtesy of HKParts.net


SEF plastic (long) and steel (short) lower safety selectors.


pic courtesy of RTG




HTH

Thanks that clears it up a great deal thanks again.