My camera is a K50, the WR lens came with it. So I think the deciding factor is the WR.

Thanks for the comments.
In the longer term something with slightly bigger aperture is in my plan.
The 18-135 is also another possibility.
I've got the Sanmsung lens up for sale with the Camera at the moment, as I doubt there's must between the two really.

Ok, so Im in the position where I have two 18-55 lenses, only one of which I want to keep.

1) DA L 18-55 AL WR
2) Sansung D Xenon 18-55 (basically the Pentax DA 18-55 AL II)

So my question is, which one do I keep? I suppose the optics are pretty much identical, so its down to the contruction and features of the lenses. Im leaning towards the DA L because of it's weather resistance, but it doesnt have the metal mount or quick shift. I can't say im bothered about quick shift, as I rarely manual focus, but the metal mount seems preferable for long term durability.
Anyone know if you can swap the mounts over so that you could convert the WR to a metal mount?

Your thoughts please?

Thanks in advance.

What sort of price are you looking at for the lens only?

Would you consider selling the 18-135 seperately?

Never mind. TBH if it wasnt red I'd probably have bitten your hand off 5 months ago.

Would you be prepared to sell the Tamron on its own? If so how much?

I think the OP wanted to put the thread to bed, not save it as a favourite!

Whilst I dont wish to be negative, what does your lens offer that say an A Series 50mm f 1.7 can't, which can be had for around £30?
As far as I can tell, your lens is difficult to focus manually, cannot use auto aperture either. So effectively its an M lens!

Well it would be cheaper to repair your K5 than buy a secondhand body of unknown history from e-bay. I take it your K5 is out of warranty?